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Lighting Duration, etc.

Contents:

  1. Light frequency / distribution
    by booth-at-hplvec.LVLD.HP.COM (George Booth) (13 Aug 93)
  2. Light frequency / distribution
    by Uwe_Behle (13 Aug 93)
  3. Light frequency / distribution
    by bhaskar-at-brtph181.bnr.ca (Shaji Bhaskar) (Mon, 16 Aug 1993)
  4. Light frequency / distribution
    by Uwe_Behle (Mon, 16 Aug 1993)
  5. Light frequency / distribution
    by Uwe_Behle (Wed, 18 Aug 1993)
  6. Light frequency / distribution
    by Uwe_Behle (9 Aug 93)
  7. do plants only grow at night or something?
    by lawrencet5-at-aol.com (LawrenceT5) (5 Feb 1995)
  8. Light requirements
    by George Booth <booth-at-hpmtlgb1.lvld.hp.com> (Fri, 21 Jul 1995)
  9. Daylength
    by krombhol-at-felix.teclink.net (Paul Krombholz) (Fri, 29 Nov 1996)
  10. Watts, lumens and hogwash
    by huntley-at-ix.netcom.com (Wright Huntley ) (Sat, 9 Nov 1996)
  11. Short night plants, etc
    by JOlson8590-at-aol.com (Sun, 1 Dec 1996)
  12. sufficient lighting...
    by krandall-at-world.std.com (Thu, 10 Apr 1997)
  13. [Q]The truth about spectrum and plant growth
    by Elizabeth Worobel <eworobe-at-CC.UManitoba.CA> (Mon, 29 Apr 1996)
  14. advantages and disadvantages of natural light
    by George Booth <booth/hpmtlgb1.lvld.hp.com> (Wed, 12 Nov 1997)
  15. Re:
    by George Booth <booth/hpmtlgb1.lvld.hp.com> (Mon, 17 Nov 1997)
  16. Green light
    by eworobe/cc.UManitoba.CA (Tue, 17 Mar 1998)
  17. gro-lux, etc bulbs
    by bae/cs.toronto.edu (Beverly Erlebacher) (23 Mar 98)
  18. Flourescent bulbs
    by bae/cs.toronto.edu (Beverly Erlebacher) (3 Apr 98)
  19. Lighting Fun
    by krandall/world.std.com (Mon, 01 Jun 1998)
  20. Lighting Fun
    by "Roger S. Miller" <rgrmill/rt66.com> (Mon, 1 Jun 1998)
  21. Light and Node Distance
    by krandall/world.std.com (Thu, 02 Jul 1998)
  22. Light Intensity vs Spectrum (long)
    by Neil Frank <nfrank/mindspring.com> (Wed, 01 Jul 1998)
  23. Making red plants really red
    by Neil Frank <nfrank/mindspring.com> (Thu, 02 Jul 1998)
  24. re: DAWN TO DUSK LIGHTING
    by "David W. Webb" <dwebb/ti.com> (Tue, 22 Sep 1998)
  25. Darkness period and plant flowering
    by krombhol/teclink.net (Paul Krombholz) (Sat, 23 Jan 1999)
  26. Ozelot sword flowering
    by Dave Gomberg <gomberg/wcf.com> (Sun, 24 Jan 1999)
  27. Watts/lumens (again?)
    by "David W. Webb" <dwebb/ti.com> (Fri, 22 Jan 1999)
  28. Aquatic Plants Digest V3 #795
    by Michael Dubinovsky <mikluha/ix.netcom.com> (Fri, 22 Jan 1999)
  29. lighting small tanks, watts per gallon rule? (long)
    by Wright Huntley <huntley1/home.com> (Mon, 15 Mar 1999)
  30. watts vs. lumens
    by Wright Huntley <huntley1/home.com> (Mon, 15 Mar 1999)
  31. watts vs. lumens
    by busko/stsci.edu (Ivo Busko) (Tue, 16 Mar 1999)
  32. RE: PAR, Lumens, Watts, etc
    by busko/stsci.edu (Ivo Busko) (Mon, 22 Mar 1999)
  33. PAR, Lumens, Watts, etc
    by Michael Dubinovsky <mikluha/ix.netcom.com> (Wed, 17 Mar 1999)
  34. PAR, Lumens, Watts, etc
    by "Roger S. Miller" <rgrmill/rt66.com> (Wed, 17 Mar 1999)
  35. Potassium and CF Lighting
    by Michael Dubinovsky <mikluha/ix.netcom.com> (Sun, 14 Nov 1999)
  36. CF Lighting Recommendations Needed
    by busko/stsci.edu (Ivo Busko) (Fri, 30 Jul 1999)
  37. CF Lighting Recommendations Needed
    by busko/stsci.edu (Ivo Busko) (Fri, 30 Jul 1999)
  38. halogen lights
    by busko/stsci.edu (Ivo Busko) (Thu, 12 Aug 1999)
  39. Potassium and CF Lighting (CF vs T5)
    by Michael Dubinovsky <mikluha/ix.netcom.com> (Tue, 16 Nov 1999)
  40. Ligthing
    by busko/stsci.edu (Ivo Busko) (Fri, 14 Jul 2000)
  41. Watts and hogwash
    by Wright Huntley <huntley1/home.com> (Thu, 13 Jul 2000)

Light frequency / distribution

by booth-at-hplvec.LVLD.HP.COM (George Booth)
Date: 13 Aug 93

In rec.aquaria, uweb-at-PROBLEM_WITH_INEWS_GATEWAY_FILE (Uwe_Behle) writes:

    [ Description of lighting factors leading Dennerle to produce a 
      good plant bulb ]

Do you know if this bulb was designed and/or spec'd by Dennerle?  It
is pretty difficult to manufacture fluorescent bulbs and most are
made by a few companies (GE, Philips, Thorn EMI) and relabeled and
sold by others.  This might be a Triton or Penn-Plax 3-phosphor bulb
repackaged.  I know the Triton bulb has a higher color temperature
than some others (6500K) and looks to have some red in it (it has a 
purplish cast compared to other bulbs). 

    One other interesting statement that I read is that there was the 
    misconception among aquarists which says: the the more light, the better. 
    Dennerle says this is only true for algae. In order to fight algae they 
    recommend leaving the lights on for a period of four hours in the morning,
    then turning them off and having them on again for another four hours. 
    They discovered that this does not have a negative effect on the plants 
    whatsoever; it does however disturb/kill algae.

From my experience, excessive light does not lead to algae as long as the 
photoperiod is correct (10-12 hours).  I believe the theory that healthy
plants will outcompete the algae for nutrients - they are able to store
and concentrate many of the nutrients, thus removing them from the 
water.  

Our one tank that has a little algae also has the poorest plant growth 
(relatively speaking).  The other tanks with robust plant growth have
no visible alage except for minor red brush algae on older leaves. 

    The reason for doing this is that in the areas where those plants come
from
    you often have noon thunderstorms with very little light. Also in the
    natural habitat of the plants you don't always have direct sun light. Most
    plants that we cultivate live in the shaded regions of the river banks.
    This means you don't need any more than 1000 - 1500 Lux for these plants.

If these plants are growing in 16-18" of water, you will need a whole
lot more than 1500 Lux at the surface to produce those levels near the
substrate or in shadows of other plants.  In our setups, 12,000 Lux
at the surface translates to ~1000 Lux at the tops of the low growing 
plants. 

    I have seen a similar recommendation before. In a book about aquarium
water 
    H. J. Krause is concerned about the high oxygen levels you see in today's 
    well-planted (the emphasis is on well-planted!) tanks.
    He recomments to leave the lights turned off for a whole day every week.
    This would happen in nature as well (on a cloudy day). Krause says:
    Watch your plants the day after you do this; they really look perked up.
    This is because the oxygen level is much lower during that "dark" day
    and nutrients can be absorbed much better with low levels of oxygen.

This is counter to the noon-rainstorm theory.  I would suspect that a 
rainstorm will highly oxygenate the water.  The raindrops should be
well saturated with O2 after their fall through the atmoshpere. 

This also doesn't bear up well to close scrutiny.  We have measured O2
levels in the morning after the fish AND plants have been consuming 
oxygen all night and have never seen it less than 7.2 mg/l (90% saturation).
At peak plant producing hours, we see 9.7 mg/l (120% saturation).  During
this time, the ORP doesn't change by more than 5-10 mv.  IMHO, Krause
is hypothesizing and has not done much experimental work to back this up. 
I wish I could find a translation of this book. 

    It also is better for the fish, if they live in an environment closer to
    their natural ones: tropical fish are used to 2 - 4 mg/l oxygen. To put
    them in water with more than that is similar to raising our atmospheric
    level from 21% to 35%. 

Are you sure these values are correct?  At sea-level and 77 F, oxygen 
saturation is 8.1 mg/l.  25-50% saturation sounds like dangerously low 
levels.  I find it difficult to believe that natural waters could ever
be that low except for relatively deep water where not much life, 
expecially plant life, exists.  I recall one reference saying 5 mg/l
is the danger point for fish but I can't locate the source, so take that
with a grain of sand. 

Anyway, when I travel from Denver's Mile-Hi altitude to sea level, I 
experience a 20% increase in atmospheric oxygen.  This does not seem
to be a bad thing when it happens :-). 

    On the spindly vs. stocky growth issue I had heard that spindly growth is
    a sign of too little light. I must say that even with lots of 
    light the internodes (piece of stem between two leafs) of some plants
    grow quite long. Apparently this depends of the level of nutrients and
    CO2. If you fertilize and have CO2, those plants (Limnonphilia,
Hygrophilia)
    grow so fast (5 cm a day) that the stem part gets really long. I have
    seen those plants under worse light conditions with no fertilization. 
    They do grow a lot slower and stockier.

I agree with this.  Most of the common stem plants have been banished 
from our CO2 injected tanks for this reason.  I have moved Hygrophila 
polysprerma from one of the "good" tanks to a non-CO2 injected 55 gal
tank.  It became denser and stockier and more attractive.  Then it 
got covered with algae. Then it died.  But it looked nice for awhile. 

-------
George

Light frequency / distribution

by Uwe_Behle
Date: 13 Aug 93

Shaji Bhaskar (bhaskar-at-brtph181.bnr.ca) wrote:
: >
: >Higher plants came originally from dry lands before they conquered the 
: >(fresh) water and thus like the yellowish part of the spectrum more. 
: >Dennerle has made experiments with Sodium-vapor lamps and their (aquatic) 
: >plants thrive. 
: 
: The data I have seen is that blue and red are the most important
: colors for photosynthesis.  Did Dennerle mention this?  How do they
: justify their claim that freshwater plants like the yellow part of the
: spectrum?

Sorry about my phrasing here. What I wanted to say is "longer wave length
than blue". This includes red too.
The importance of blue stems from experiments done years ago on *algae*.

: 
: Why not carry this idea through to its logical limit, and simply use
: natural light?  It seems natural light has all the advantages that
: Dennerle's lighting has, and it is free :-).
: 

I shure would like to do that and save on my electric and bulb replace-
ment bill. It's just so difficult to turn the sun on at 11 am and off
at 11 pm, and even if I could I guess a few people would mind :-).

What I really wanted to say with this article was that it is possibly
questionable whether metal halides give you a real advantage for 
*freshwater* tanks. I am considering those too, but I will wait for
an article in the September issue of DATZ, a german magazine. They
have started a series about lighting and in the Sept. issue they are
going to tell us what the "best light source" is. 
Always keep in mind that those brochures (and Dennerle is no exception)
are printed in order to increase sales of their products.

Uwe

--
NAME    Uwe Behle, HP Boeblingen Instruments Division
EMAIL   uweb-at-hpbbn.bbn.hp.com (internet)\
        df3du-at-db0sao.ampr.org (packet radio)
SNAIL   Hewlett-Packard GmbH, BID R&D, Herrenberger Str. 130,\
        D-71034 Boeblingen, Germany
PHONE   011-49-7031-142016 (work)
FAX     011-49-7031-143883 (work)

Light frequency / distribution

by bhaskar-at-brtph181.bnr.ca (Shaji Bhaskar)
Date: Mon, 16 Aug 1993

In article <CBotL7.Lot-at-hpbbrd.bbn.hp.com> uweb-at-hpbbn.bbn.hp.com writes:
>Shaji Bhaskar (bhaskar-at-brtph181.bnr.ca) wrote:
>: >
>: >Higher plants came originally from dry lands before they conquered the 
>: >(fresh) water and thus like the yellowish part of the spectrum more. 
>: >Dennerle has made experiments with Sodium-vapor lamps and their (aquatic) 
>: >plants thrive. 
>: 
>: The data I have seen is that blue and red are the most important
>: colors for photosynthesis.  Did Dennerle mention this?  How do they
>: justify their claim that freshwater plants like the yellow part of the
>: spectrum?
>
>Sorry about my phrasing here. What I wanted to say is "longer wave length
>than blue". This includes red too.
>The importance of blue stems from experiments done years ago on *algae*.

From what I know, Sodium vapor lamps have a few spikes in yellow part
of the spectrum, and none in the red part.  Is this a specially
modified lamp?

>Always keep in mind that those brochures (and Dennerle is no exception)
>are printed in order to increase sales of their products.

I am sure someone will come up with a MoneyGrabber timer that will
turn your lights on and off at random to produce Real (TM) Daylight,
the optimum lighting for all creatures great and small :-).

>
>Uwe
>
>--
>NAME   Uwe Behle, HP Boeblingen Instruments Division
>EMAIL  uweb-at-hpbbn.bbn.hp.com (internet)\
>       df3du-at-db0sao.ampr.org (packet radio)
>SNAIL  Hewlett-Packard GmbH, BID R&D, Herrenberger Str. 130,\
>       D-71034 Boeblingen, Germany
>PHONE  011-49-7031-142016 (work)
>FAX    011-49-7031-143883 (work)

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Plants ar green.  Then they turn brown.  Then they die.  NOT!
Shaji Bhaskar * BNR, Research Triangle Park, NC 27709, USA * (bhaskar-at-bnr.ca)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Light frequency / distribution

by uweb-at-PROBLEM_WITH_INEWS_GATEWAY_FILE (Uwe_Behle)
Date: Mon, 16 Aug 1993

I just re-read an article in the DATZ (a German magazine for aquarists) dating
August 1993.
There is some information on light colour that goes into the same direction
as my earlier posting.
1) Some 20-30 years ago a guy named McCree found out that certain algae
   have two sensitivity peaks for photosynthesis. One is in the red part
   and one in the blue part of the spectrum.
   The old statement that red light produces thin long-stretched leaves
   and blue light short growth dates from that time.
   McCree's results were taken to be valid for higher plants as well.
   This proved to be wrong.
2) When McCree did some experiments of the same kind with higher plants,
   he found indeed totally different data.
   The big peak is now at 620-680nm (red), the sensitivity curve then drops
   of to 50% for colours between 400-550nm (green-blue). I am sure you
   have seen this curve in several books on plants. This is the reason
   that (most) plants look green.
3) Dr. O. Elgersma (Philips) generated this curve from McCree's results.
   It is the average sensitivity based on many of the experiments McCree
   did.
4) In 1982 Philips Corp. did a lot of experiments in order to find out 
   the effects of different light colours on aquarium plants. The 
   following plants were used (because of their fast growth):
        Hottonia inflata
        Limnophilia sessiflora
        Ludwigia natans
        Bacopa amplexicaulis
        Hygrophilia polysperma
        Rotala macandra
   The surprising results were that the influence of colour was less than
   10 percent!

5) The results are applicable for all aquatic plants because all aquatic
plants
   contain the same type of chlorophylls as the land-based plants.
   Algae contain additional chlorophylls that are not found in higher plants.
   From McCree's experiments it is obvious that these additional chlorophylls
   are responsible for the sensitivity to blue light.

Bottom line:
============

   It does not matter what colour of light you provide for your aquarium
   plants. Choose a colour that makes it look good for you.
   If you are not interested in algae (fresh water people usually are not)
   you can additionally try to avoid the blue part of the spectrum
   (or keep it to a minimum). This also means that high light temperatures
   (>5500K or so) are better suited for a salt water aquarium.
   ---> Your mileage may vary.<---

   The September issue of DATZ will address the question "Is there a special 
   aquarium light?". It will be interesting to see what their answer is.

   Uwe

--
NAME    Uwe Behle, HP Boeblingen Instruments Division
EMAIL   uweb-at-hpbbn.bbn.hp.com (internet)\
        df3du-at-db0sao.ampr.org (packet radio)
SNAIL   Hewlett-Packard GmbH, BID R&D, Herrenberger Str. 130,\
        D-71034 Boeblingen, Germany
PHONE   011-49-7031-142016 (work)
FAX     011-49-7031-143883 (work)

Light frequency / distribution

by uweb-at-PROBLEM_WITH_INEWS_GATEWAY_FILE (Uwe_Behle)
Date: Wed, 18 Aug 1993

George Booth (booth-at-hplvec.LVLD.HP.COM) wrote:
: In rec.aquaria, uweb-at-PROBLEM_WITH_INEWS_GATEWAY_FILE (Uwe_Behle) writes:
: 
:     [ Description of lighting factors leading Dennerle to produce a 
:       good plant bulb ]
: 
: Do you know if this bulb was designed and/or spec'd by Dennerle?  It
: is pretty difficult to manufacture fluorescent bulbs and most are
: made by a few companies (GE, Philips, Thorn EMI) and relabeled and
: sold by others.  This might be a Triton or Penn-Plax 3-phosphor bulb
: repackaged.  I know the Triton bulb has a higher color temperature
: than some others (6500K) and looks to have some red in it (it has a 
: purplish cast compared to other bulbs). 

I suppose they cooperated with Philips on that. It says Dennerle on the
bulb. They show the spectrum of the lamp in one of their brochures. You'd
have to judge based on that whether it is one of the above bulbs.

: 
:     One other interesting statement that I read is that there was the 
:     misconception among aquarists which says: the the more light, the
better. 
:     Dennerle says this is only true for algae. In order to fight algae they 
:     recommend leaving the lights on for a period of four hours in the
morning, 
:     then turning them off and having them on again for another four hours. 
:     They discovered that this does not have a negative effect on the plants 
:     whatsoever; it does however disturb/kill algae.
: 
: From my experience, excessive light does not lead to algae as long as the 
: photoperiod is correct (10-12 hours).  I believe the theory that healthy
: plants will outcompete the algae for nutrients - they are able to store
: and concentrate many of the nutrients, thus removing them from the 
: water.  
: 
: Our one tank that has a little algae also has the poorest plant growth 
: (relatively speaking).  The other tanks with robust plant growth have
: no visible alage except for minor red brush algae on older leaves. 

I agree. It does not lead to algae. I have very bright light here too. I am
sure though that it is a absolute overkill for some of my plants. Also
light tends to increase the oxygen level which in turn increases the
Redox potential (or at least is connected to it). A high redox potential is
known to be better for algae than a low one. Let's say it increases the odds.

: If these plants are growing in 16-18" of water, you will need a whole
: lot more than 1500 Lux at the surface to produce those levels near the
: substrate or in shadows of other plants.  In our setups, 12,000 Lux
: at the surface translates to ~1000 Lux at the tops of the low growing 
: plants. 
: 
:     I have seen a similar recommendation before. In a book about aquarium
water 
:     H. J. Krause is concerned about the high oxygen levels you see in
today's 
:     well-planted (the emphasis is on well-planted!) tanks.
:     He recomments to leave the lights turned off for a whole day every week.
:     This would happen in nature as well (on a cloudy day). Krause says:
:     Watch your plants the day after you do this; they really look perked up.
:     This is because the oxygen level is much lower during that "dark" day
:     and nutrients can be absorbed much better with low levels of oxygen.
: 
: This is counter to the noon-rainstorm theory.  I would suspect that a 
: rainstorm will highly oxygenate the water.  The raindrops should be
: well saturated with O2 after their fall through the atmoshpere. 

I turned the lights off last Wednesday for a whole day and measured oxygen
after a dim (not completely dark) phase of 36 hours. I still had 8mg/l
oxygen in the water. The plants DID look like they liked it though.

: 
: This also doesn't bear up well to close scrutiny.  We have measured O2
: levels in the morning after the fish AND plants have been consuming 
: oxygen all night and have never seen it less than 7.2 mg/l (90% saturation).
: At peak plant producing hours, we see 9.7 mg/l (120% saturation).  During

I have the same thing happen to me and I dont like having the plants
bubble like crazy in the afternoon.

: this time, the ORP doesn't change by more than 5-10 mv.  IMHO, Krause
: is hypothesizing and has not done much experimental work to back this up. 

I dont know how he backs up his statement that the Redox potential is
linked to the oxygen concentration. He just says that the concentration
of other substances responsible for the Redox is so weak that the one
oxidator with the highest concentration (oxygen) dominates. 
He has made numerous trips to the places where our plants/fish come from
and he has made a lot of measurements there (Redox and oxygen). Maybe
that's where his claim comes from. He also discourages people from using
chemical agents to determine the oxygen concentration. They spoil too fast.
He recommends a probe which is accurate to 0.1mg/l (and also too expensive
for most hobbyists).

Another point, George: Krause also says in his book that having a Redox
probe in the tank permanently will show you lottery numbers for the Redox
voltage. He recommends to clean the probe EVERY time you make a measurement:
1) use a non-abrasive detergent to thouroughly clean the probe.
2) put the probe into 15% HCl for 5 minutes.
3) rinse with distilled water
4) put the probe into 5% FeSO4 solution for 2 minutes
5) rinse the probe with distilled water.
6) do your measurement. Most important: do it in moving water (non stagnant)
   this excludes taking a sample from the water and measuring the sample.
   Also wait at least 15 minutes before you take a reading and watch that the
   value stays constant.

: 
:     It also is better for the fish, if they live in an environment closer to
:     their natural ones: tropical fish are used to 2 - 4 mg/l oxygen. To put
:     them in water with more than that is similar to raising our atmospheric
:     level from 21% to 35%. 
: 
: Are you sure these values are correct?  At sea-level and 77 F, oxygen 
: saturation is 8.1 mg/l.  25-50% saturation sounds like dangerously low 
: levels.  I find it difficult to believe that natural waters could ever
: be that low except for relatively deep water where not much life, 
: expecially plant life, exists.  I recall one reference saying 5 mg/l
: is the danger point for fish but I can't locate the source, so take that
: with a grain of sand. 
:
There are fish and there are fish. Krause states that fish living in mountain 
creeks does not tolerate low oxygen concentration well. Most fish we have
does not come out of those cooler mountain creeks. It's hard to say whether
a fish feels uncomfortable if it has to breathe faster; the fact is that
there are a lot of biotopes with an oxygen concentration of 2 - 4mg/ltr.
Don't try to replicate this in your aquarium. Your little puddle is not
stable enough to run that risk. You should, however, try to keep oxygen
level between 4 and 6mg/l. 
Krause shows pictures of thriving plant tanks with only 3 - 5 mg/l oxygen.

: 
: Anyway, when I travel from Denver's Mile-Hi altitude to sea level, I 
: experience a 20% increase in atmospheric oxygen.  This does not seem
: to be a bad thing when it happens :-). 

I don't think is so bad either :-)

: 
:     On the spindly vs. stocky growth issue I had heard that spindly growth
is
:     a sign of too little light. I must say that even with lots of 
:     light the internodes (piece of stem between two leafs) of some plants
:     grow quite long. Apparently this depends of the level of nutrients and
:     CO2. If you fertilize and have CO2, those plants (Limnonphilia,
Hygrophilia)
:     grow so fast (5 cm a day) that the stem part gets really long. I have
:     seen those plants under worse light conditions with no fertilization. 
:     They do grow a lot slower and stockier.
: 
: I agree with this.  Most of the common stem plants have been banished 
: from our CO2 injected tanks for this reason.  I have moved Hygrophila 
: polysprerma from one of the "good" tanks to a non-CO2 injected 55 gal
: tank.  It became denser and stockier and more attractive.  Then it 
: got covered with algae. Then it died.  But it looked nice for awhile. 
: 
There is a picture in the "Optimum Aquarium" that compares plants under 
different growth conditions. The most interesting ones are the last two
(plants with fertilizer and no CO2 versus plants with fertilizer and
CO2). I must say that I find the plants grown without CO2 a lot more 
attractive. IMHO Horst/Kipper picked a bad example to promote CO2
fertilization.
Stem plants grow too fast under those conditions. There is no doubt
that  CO2 is a big advantage for a lot of other plants, though.

Uwe 

--
NAME    Uwe Behle, HP Boeblingen Instruments Division
EMAIL   uweb-at-hpbbn.bbn.hp.com (internet)\
        df3du-at-db0sao.ampr.org (packet radio)
SNAIL   Hewlett-Packard GmbH, BID R&D, Herrenberger Str. 130,\
        D-71034 Boeblingen, Germany
PHONE   011-49-7031-142016 (work)
FAX     011-49-7031-143883 (work)

Light frequency / distribution

by Uwe_Behle
Date: 9 Aug 93

George Booth (booth-at-hplvec.LVLD.HP.COM) wrote:
: In rec.aquaria, rpt-at-wdl1.wdl.loral.com (Richard P Toren) writes:
: 
:     I am looking for documentation about how the frequency spectrum
:     and intensities  effect plants and other parts of the aquarium.
:     I have heard simplisticly that 'red' light leads to tall spindly
:     growth, while 'blue' gives short stocky growth.
: 
: You could get very scientific about all this and determine proper
: wavelengths, combinations of intensity and wavelength to simulate
: sunlight or optimize growth, sequencing of various color temperatures
: to simulate morning, noon, afternoon lighting and diurnal effects.
: But you would just drive yourself crazy trying to find commercial 
: supplies to meet your specs.  
: 
: I would recommend "full spectrum" lighting for a nice overall balance 
: of wavelengths optimized for photosynthesis and correct color to 
: give a natural look to the eye.  Actinic and/or "plant lights" may
: have radiation in the proper bands for photosynthesis, but they look 
: like sh*t, IMHO.  They also are not as intense as full spectrum bulbs.  
: Of course, they are cheaper, if that matters. 
: 
: We have a mixture of Penn-Plax "Ultra TriLux" and Triton bulbs.  The
: plants like the mixture and the color balance is great.  A good way
: to check color balance is to take some photos with "daylight" film
: like KodaColor.  If the colors in the photos look like the colors 
: in the tank, you have a good simulation of typical sunlight.
: 
: -------
: George

I just came across a new brochure from a German aquatic plant nursery 
(Dennerle) on plants and algae. They claim that algae, originally coming
from the ocean before moving into fresh water, thrives best on the blue
part of the spectrum. 

Higher plants came originally from dry lands before they conquered the 
(fresh) water and thus like the yellowish part of the spectrum more. 
Dennerle has made experiments with Sodium-vapor lamps and their (aquatic) 
plants thrive. 

Unfortunately, the light of those lamps does look very unpleasant. They 
have therefore developed a special lamp that does contain a significant 
amount of red/yellow in its spectrum and keeps the blue part only to provide 
a pleasant colour of light. 

They also claim that the lamps with the high percentage of blue in its 
spectrum come originally from salt water aquariums where you DO want to 
have algae. Using those lamps for fresh water may lead to the same thing: 
while being of neutral value for the higher plants it does give the algae 
an edge. Those high-intensity blueish lamps have been transferred from
salt water to fresh water too carelesslay, without addressing the different
needs of fresh water plants (I am using lights with high intensity in
the blue spectrum as well, so this is some point I will have to think
about). Please note that this is just one contribution to algae problems;
it's by far not the only and most important one.

One other interesting statement that I read is that there was the 
misconception among aquarists which says: the the more light, the better. 
Dennerle says this is only true for algae. In order to fight algae they 
recommend leaving the lights on for a period of four hours in the morning, 
then turning them off and having them on again for another four hours. 
They discovered that this does not have a negative effect on the plants 
whatsoever; it does however disturb/kill algae.

The reason for doing this is that in the areas where those plants come from
you often have noon thunderstorms with very little light. Also in the
natural habitat of the plants you don't always have direct sun light. Most
plants that we cultivate live in the shaded regions of the river banks.
This means you don't need any more than 1000 - 1500 Lux for these plants.

I have seen a similar recommendation before. In a book about aquarium water 
H. J. Krause is concerned about the high oxygen levels you see in today's 
well-planted (the emphasis is on well-planted!) tanks.
He recomments to leave the lights turned off for a whole day every week.
This would happen in nature as well (on a cloudy day). Krause says:
Watch your plants the day after you do this; they really look perked up.
This is because the oxygen level is much lower during that "dark" day
and nutrients can be absorbed much better with low levels of oxygen.

Algae don't like a low oxygen level (= low redox - potential) at all.
G. Hueckstett has observed that if you lower the redox potential (=O2)
the first to go are the green algae, followed by the red and finally 
by the brown (I don't know where the blue-green fits in). Hueckstett
is in charge of a bunch of saltwater tanks in some biology department
at a Max-Planck institute (Heidelberg?) for a period of some ten years.
Reading his book on aquarium water is really fun because of the dry
irony he uses to make some of the so called advances in aquaristic
appear ridiculous (One of these is by the way an UGF), but this is
getting too far away from the original topic.

It also is better for the fish, if they live in an environment closer to
their natural ones: tropical fish are used to 2 - 4 mg/l oxygen. To put
them in water with more than that is similar to raising our atmospheric
level from 21% to 35%. 

I find these statements very interesting. Both quoted sources are well
known people with a lot of experience in aquatic plants. Dennerle is
competing directly with Dupla with their products and on top they have
a 24 hour mail order service for high quality water plants, 80% coming
from their own greenhouses. In that respect they have more experience
than Dupla and some of their recommendations differ quite a bit
(Light and gravel heating).

I will implement the one "dark" day a week. If it works well I'll
post it.

On the spindly vs. stocky growth issue I had heard that spindly growth is
a sign of too little light. I must say that even with lots of 
light the internodes (piece of stem between two leafs) of some plants
grow quite long. Apparently this depends of the level of nutrients and
CO2. If you fertilize and have CO2, those plants (Limnonphilia, Hygrophilia)
grow so fast (5 cm a day) that the stem part gets really long. I have
seen those plants under worse light conditions with no fertilization. 
They do grow a lot slower and stockier.

Uwe
--
NAME    Uwe Behle, HP Boeblingen Instruments Division
EMAIL   uweb-at-hpbbn.bbn.hp.com (internet)\
        df3du-at-db0sao.ampr.org (packet radio)
SNAIL   Hewlett-Packard GmbH, BID R&D, Herrenberger Str. 130,\
        D-71034 Boeblingen, Germany
PHONE   011-49-7031-142016 (work)


do plants only grow at night or something?

by lawrencet5-at-aol.com (LawrenceT5)
Date: 5 Feb 1995
Newsgroup: rec.aquaria,sci.aquaria

Pat,

Plants *DO* grow primarily at night as they are busy converting CO2 H2O
and Light Energy into carbohydrates during the day.  They call upon their
stored energy at night for growth.  As a matter  of fact, if you light
plants strongly from one direction, they will grow in that direction
because the light INHIBITS the growth on the side toward the light and
allows the other side to grow more which tilts the plant toward the light
source.

Check out light phase and dark phase photosynthesis in any decent biology
text.



Larry Tagrin



Light requirements

by George Booth <booth-at-hpmtlgb1.lvld.hp.com>
Date: Fri, 21 Jul 1995

The discussion on light requirements is tending toward opinions based
on "What works for <insert your name here>". This is all well and
good, but doesn't provide much basis for determining "what will work
for me" based on "what works for you".  There are quite a few
variables:

1) Your tank size
2) Your water conditions
3) Your maintenance regimen
4) Your specific plants
5) Your aquascaping particulars
6) Your criteria for "success"

The simplified "watts per gallon" criteria may be useful for beginners
to show them that the 15 watt bulb that comes with their 29 gallon
tank is insufficient, but doesn't really help that much.  A more
pseudo-scientific method is sorely needed that brings together the
known parameters. Let me try to start a discussion by rambling a bit.
Feel free to comment.

Success criteria
- ----------------

A "successful" plant tank can mean almost anything.  Newbies may be
satisfied if the plants don't die right away.  Casual aquarists might
be happy of the plants stay green and they don't have to weed the
tanks every month and don't need to mortgage the house to buy
fertilizers. Enthusiasts want actual growth and propagation so they
can impress their friends and win HAP points.  Fanatics like me want
massive growth and aren't happy unless the plants are supersaturating 
the tank with O2 and can be harvested for sale at plant auctions to
pay for the high tech products being used.

The oft-maligned Kevin Osborne is perfectly happy with his smattering
of non-demanding plants.  I would be bored to tears. 

I wonder if we could develop some objective terms to describe our
successes?  Somehow I think the results obtained with a gro-lux and
cool white bulb and a bag of breath are different than results
obtained with obscenely expensive triton and ultra trilux bulbs and
automated CO2 injection.  Both techniques are satisfying to their
proponents but need to be quantified somehow for someone trying to
decide which route to go.   

 
Light requirements for plants
- -----------------------------

Different plants require different amounts of light energy for growth. 
Growth is limited by the amount of carbohydrates that are created
during photosynthesis.  Photosynthesis is limited by the amount of
light energy available (required intensity and spectrum) and the
amount of nutrients and CO2 available.  At a certain threshold of
energy, no photosynthesis will occur. Above that threshold, more and
more photosynthesis occurs until an upper threshold is reached.  See
the discussion in "Dynamic Aquaria" for more details.  

There is precious little information about how much energy various
plants need. The only quantitative data I've found is in "The Complete
Book of Aquarium Plants" (Allgayer and Teton, translated from French). 
The following table is from that book (roughly treanslated):

                Amount of lighting in lumens/m^2 (lux)
Plant genera    500 1000  1500 2000 2500 3000 3500 4000 4500 5000
- -----------------|----|----|----|----|----|----|----|----|----|
surface plants      |------------------------------------------->
Myriophyllum        |--------------------------X----|
Bacopa            |--------X---------|     
Hottonia             |-------X--------------------------------|
Ludwigia             |-------X---------------------------|
Aponogeton           |--------X----------------------|
Ceratopteris         |---X-----------------------------|
Nomaphila            |--------X---------------------|
Rotala               |--------X------------------|
Vallisneria        |-------X--------------|
Echinodorus      |--X-------------|
Sagittaria        |-X---------|
Cryptocoryne     |-X--------|
Marsilea         |-X--------|
Micorsorium      |-X--------|

"X" indicates the optimum for each genera.

Depending on the plants in the aquarium, you can decide how much light
intensity you need *at the plant*.  For a tank holding Ludwigia,
Rotala and Nomaphila, the plants would need over 1000 lux at the
leaves.  Foreground plants like E. tenellus would need around 600 at
the leaves.  The upper leaves will get plenty of light so you need to
consider the needs of the lower leaves. Once you know the intensity
required at the leaf, you can figure out how much you need at the
*bulb*.

Light loses intensity very quickly in water.  What we need is a chart
that shows how much is lost so we can determine how much light is
needed at the surface to produce the required amount at the depth we
desire. The Allgayer book has such a chart but it was apparently
garbled in the translation and is useless. There are aquascaping
specific considerations, also.  Do tall plants overshadow forground
plants?  Are emersed leaves blocking the light?  Also, light is
reflected from the aquarium sides so that plants near the glass get
more light than plants in the middle.  Perhaps such a chart could take
"typical conditions" into account.  Perhaps actual measurements with a
luxmeter could be taken. 

If you know how much light is needed at the surface, you can determine
approximately how many lumens you need in the hood.  If all the lumens
from the bulbs could be focused onto the water surface, the lux at the
surface is (total lumens / area of surface in meters^2).  Derating
factors such as reflector efficiency and hood configuration could be
developed. 

You would also need to take in account the reduction in lumens over
time as the bulbs age.  If you designed your light system for just the
right amount of lumens based on the initial lumen rating, it would be
suboptimal a short time after startup and would never be right unless
all the bulbs were changed at once.  So a factor considering something
like 25% new bulbs, 25% almost new bulbs, 25% getting old bulbs and
25% old bulbs would need to generated. 
 
Hmmph, maybe "2 watts per gallon" isn't so bad after all ;-).

As for light type, there is no clear data that indicates whether
blue-red or full spectrum light is "better" for growth.  I prefer the
appearance of full spectrum light.  The intensity of bulbs is
expressed in "lumens" which is weighted towards humnan sensitivities.
There are no commerical ratings geared towards plants so we are stuck
with lumens.  The output in lumens of a gro-lux bulb looks poorer than
a full-sepctrum bulb even though the "useful" light energy *may* be
the same (I don't know for sure).  But anything we come up with will
have to deal with lumens with perhaps some factor for the bulb type.

George


Daylength

by krombhol-at-felix.teclink.net (Paul Krombholz)
Date: Fri, 29 Nov 1996

>I just read in Aquarium Pflanzen, that Echinodorus sp. can be induced to
>flower by providing them with either a long day or a short day. Some species
>are day length neutral and flower all the time.
>
>Nowhere, however, can I find the definition of "day". Is a short day,
>a period with less than 12 hours of illumination - and then total black-out?
>Or does the night light in the corner put out enough photons to make the plant
>"think" it still lit?  What about the car lights that strike the window
>blinds, opposite from the tank? Does the mometary bright flash have an
>effect?
>If no, how long is too long?
>Also, over what period do the plants need a short day before the flower?
>One night? One week? Several weeks?
>Sorry for all these questions, but I would really like to see my swords to
>flower again and I think this is an area that hasn't received a lot of
>press. :-)
>
>Michael

Daylength control of flowering in plants is complicated, In general, the
mechanism that plants use to measure daylength really measures the length
of the night.   Long day plants should, more correctly, be called short
night plants, where the night has to be shorter than X hours.  Short day
(really long night) plants have to have a night longer than X hours.  Just
what X is, varies with the plant species, and even variety.  There is a
plant pigment, phytochrome, that exists in two forms, Pr and Pfr.  Pr has
an absorbtion maximum at around 600 nanometers (red) and Pfr has an
absorbtion maximum at 720 nm (far red). Red light is absorbed by Pr and
converts it to Pfr.  Far red light is absorbed by Pfr and converts it to
Pr.  Pfr in the dark slowly converts to Pr, and it is this slow conversion
that is the main 'clock' by which the plant measures night length.   (Told
you it was complicated!)

Flowering in short night plants is stimulated _only_ if the level of Pfr
does not drop below a certain level.  This would happen in a night shorter
than X hours.  Flowering in long night plants is stimulated if the level of
Pfr drops below a certain level.  This would happen in a night longer than
X hours.

Sunlight has a balance of red and far red light that leaves plants with a
mix of about 60% Pfr, 40% Pr at sunset.  The phytochromes are relatively
sensitive to dim light, however, and street lights, which are higher in red
than far red light can mess up the local weeds growing nearby, and cause
them to stay vegetative too long into the fall season, resulting in their
being killed by frosts before they can set seed.  A brief one minute
exposure of red light in the middle of the night can convert a bunch of Pr
to Pfr and 'reset' the plant's clock to zero.  It basically breaks up a
long night into two short nights, and would cause a short night plant to
bloom and a long night plant not to bloom.  A brief one minute pulse of far
red light can convert a bunch of Pfr to Pr, and make the plant think it had
a long night.  With some plants, all it takes is one night of the critical
length to stimulate flowering.  With others it takes more than one, up to a
week of nights.

I have always wanted to do some experimenting with pulses of red and far
red light on my tank plants, but havn't gotten around to doing it yet.  It
is a lot easier to give a tank a short night than a long one, because room
lights left on after the tank light go off can contribute to the conversion
of Pr to Pfr.  A breif flash of car lights, however, probably wouldn't have
any appreciable effect.  If one is serious about giving a long night, one
should keep the tank pretty much in darkness after the tank lights go off.
That proviso makes giving the tank a long day followed by a minute or two
of far red light just after the lights go off an attractive alternative,
because the shot of far red converts what would have been a short night to
a long one by setting the plant's clock ahead.  Does anyone out there know
where I can get a relatively cheap filter that lets mostly far red light
(730) through?

Regards,


Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In rainy Jackson, Mississippi. 


Watts, lumens and hogwash

by huntley-at-ix.netcom.com (Wright Huntley )
Date: Sat, 9 Nov 1996

Hi folks,

The recent thread on this subject prods me to finally release an old note I did 
on it a while back. Re-reading it, it still sounds reasonable, so here it is. 
If you have trouble with the figure, try loading it into an editor without a 
proportional font.

Lumens, Lux, Foot-candles and other photometric terms are based entirely on how 
the average human eye perceives light. Standard observers were defined by 
testing many individuals and averaging the results. CRI, Color Temperature and 
a host of other common terms all derive from the original work of the 
International Committee on Illumination (ICI, or CIE in the French version), 
dating back almost 60 years.


Plants don't *have* human vision, so some judgement is required when trying to 
use human-sensitive terms to define what our plants need. Sometimes, the exact 
opposite of what we want can come from being too slavish to the desire for 
"more lumens per Watt." To illustrate this point, look at the relative spectral 
sensitivity curves of Figure 1. Plant growth rate is plotted as xxx, while 
human eye sensitivity (Photopic, or daylight adapted) is plotted as ooo. The 
vertical scales are adjusted so that there is approximately equal area under 
each curve.

The dip in the green for plants is evident (they *do* reflect more green away) 
and the green growth sensitivity is only about 1/4, compared to what our eye 
perceives. In the violet and deep red, the plants have thousands of times more 
sensitivity than the human eye. Our visual response in the visible blue and red 
is only about 10% what it is in green and yellow.

Any sensible phosphor designer will tailor his lamp to match the human eye 
curve, *if* the objective is to maximize lumens per Watt. This means that 
phosphors wasting any energy in the blue and red are eliminated. The standard 
"cool white" flourescent bulb is a superb example of this kind of engineering 
raised to a very high art. The spectrum of cw bulbs closely matches the human 
scotopic curve, yielding a lot of lumens/Watt, but only mediocre plant-growth 
response. Photos taken under cw flourescents end up with a sickly green tint.

Most of us like to actually look at our plant tanks, so the cheaper 
"plant/aquarium" bulbs that have big spikes in the blue and red, with almost no 
green may give good growth, but should be only of interest to the pot grower or 
other esthetically uninvolved user. A magenta glow is not very pleasing in an 
underwater scene. [Spectacular for a tank of neons or cardinals, tho.]

The ideal spectrum for combined visual and growth purposes is a broad-band 
source. In fact, an ordinary incandescent bulb, operating at a color 
temperature of about 3200K, is nearly perfect. The one small flaw is the large 
amount of heat it generates, for it doesn't fall off at wavelengths above 
750nm, like the plant curve does. Halides are more efficient, so are even 
better, but the heat is still a big problem.

Flourescent tubes are available that give pleasing color rendition, but still 
provide better growth efficiency than "cool white." I have grown lush Riccia 
fluitans under an 8W cool-white tube, for there is nothing that says plants 
have *no* response in the visual region. It just *looks* very bright and 
doesn't give the best plant growth.

For about four times the plant growth rate at a slight perceived drop in 
brightness, either a daylight or GE Chroma 50 will give pleasant colors and 
vigorous plant growth. Phillips Schedule 35 and most tri-phosphors work well, 
too. None of these tubes are very expensive. I will reserve my thoughts on the 
poorly-designed, unreliable, short-lived specialty tubes, called aquarium 
bulbs, sold for four to ten times the price of these suggested, well-engineered 
products. 

Esthetically, I like a 50-50 combination of daylight and Chroma 50. With only 
80W (2 40W tubes) in a shop-light fixture, over a 55G tank, the growth-limiting 
factor definitely is CO2, not the light. That's only 1.5 Watts/Gallon, far 
below the frequently suggested 2-4 W/G. Even with lower lumens or lumens/Watt 
ratings, they are the *growth* equivalent of about 6W of "cool white" tubes.





     Photopic Human Eye-sensitivity Curve -- o o o (Lumens definition base)

     Plant Growth Spectrum -- x x x ( Growth rate vs spectral power density)
     ______________________________

1  _                                 o
 |                                 o   o
 |
 |                               o       o
 |
 |                                        o
 |                             o
 |                                          o
 |                            o              o
 |
..5_                          o                 o
 |
 |                         o                     o
 |                                                o                 x  x
 |               x       o                         o  x                 x
 |          x         x o                 x         o
 |                    o         x                    o   
 |    x             o                                  o                 
 |                o                                     o
 |              o                                         o               
0|         o                                                 o             
 |____|____|____|____|____|____|____|____|____|____|____|____|____|____|
    400                 500                 600                 700     nm
   UV   Violet  Blue        Green     Yellow   Orange   Red          IR

                        Figure 1. Eye vs Plant-Growth Curves



I sincerely hope this helps clarify how we look at illumination sources for 
both our visual stimulation and our plant growth.

My plant curve was derived from textbooks and was taken from data on emersed 
plants. It is closer to our reality than the many studies I saw on algal 
growth, which lends itself to lab analysis, but doesn't reflect higher-plant 
reality very well.

Lumens are for "looking at..." Watts are energy. Neither is the whole answer. 
Use good judgement in selecting the best for your tank.

Wright


- -- 

Wright Huntley (408) 248-5905 Santa Clara, CA USA huntley-at-ix.netcom.com


Short night plants, etc

by JOlson8590-at-aol.com
Date: Sun, 1 Dec 1996

Paul Krombholz' explanation of short night versus long night plants is
entirely correct, and _very well stated._  (Thanks, Paul, it saved me from
looking the entire subject up again.  I used to teach this to Extension
Service audiences, but it has been quite a few years and I didn't want to
goof up the explanation.) 

To find deep red bulbs or filters - 
(a) Try a photo shop. Many black-and-white photographic films and papers
used
to be totally insensitive to red light, hence both pure deep red bulbs and
deep red filters for "safe lights" were used.  

(b) A 9-watt deep red "compact fluorescent" bulb is available. I got some
at
Mail Order Pet Shop.  I have NOT checked to see if they would trigger plant
flowering, but they do seem to work pretty well if you just want to see
what
the night-active fish are doing. 

Hope this helps.


sufficient lighting...

by krandall-at-world.std.com
Date: Thu, 10 Apr 1997

>Hi everyone!  I'm rather new to the hobby of keeping aquatic plants and 
>I've decided to set up one of my old 20 gal "high" tanks as planted 
>tank.  The only problem is that I can't figure out how to provide 
>sufficient lighting for the tank.  I figure that because the tank is 20 
>gal that I would want to provide 80 to 100 watts of light.  My one bulb 
>for the hood is only 15 watts!!  How could I provide enough light?  Is 
>there anyway to build my own hood (perhaps 4 bulbs in the fixture)?  
>Could anybody offer some possible solutions?  Any answer (or multiple 
>answers :) ) would be appreciated!

My rant for the day :-)

This is another area where many people seem to be falling into the common
American faulty thinking, "If some is good, more must be better".  While
15W on a 20G tank is certainly on the dim side,  80-100W is _WAY_ in the
other direction.  I see no good reason to use light levels this high.  I
have _never_ failed with a plant for lighting reasons with light in the
3W/G range in a tank of less than 22" in depth. (some people seem to feel
that these higher levels are necessary in deeper tanks, and since I've
never worked with a deeper tank personally, I can't comment)  Beyond 3W/G
on a smaller tank, and you are simply wasting money on electricity, and
guaranteeing that you will need to use more supplemental CO2 and trace
elements than in a more moderately lit tank.  I am not suggesting that it
isn't possible to reach a steady state in a tank like this, but it
certainly won't be easier, and it _might_ be harder than with 3W/G.

Personally, I run the two 20H tanks that we have with 40W over each.
(easily accomplished with 2 20W strip lights)  Both have _excellent_
growth, and contain many species including several "high light" species
like Bacopa, Acorus, Lilaeopsis and Rotala macrandra.  All of these plants
grow well enough to require regular division, and are lush and green.
(Rotala is lush and red<g>)


Karen Randall
Aquatic Gardeners Association


[Q]The truth about spectrum and plant growth

by Elizabeth Worobel <eworobe-at-CC.UManitoba.CA>
Date: Mon, 29 Apr 1996
Newsgroup: rec.aquaria.freshwater.plants

On Thu, 25 Apr 1996, Aquanaut wrote:

> What spectrum color do plants like?  More blue or more red?
> Most of what I've read about compact fluorescent bulbs say to use 5000K 
> range bulbs (this range has less red and more blue).  But some say to 
> use more redish bulbs which would be 2800K range.  What's the real 
> story?!

The real story is that it doesnt matter. Plants are superbly adapted to 
assimilate ALL wavelengths between 400 and 700 nm. There is a peak in 
absorption efficiency in the red and blue region but green and yellow 
wavelengths are also absorbed. All you need for excellent vegetative 
growth are enough cool white fluorescent bulbs (2 to 4 W per gallon). The 
beauty of cool white bulbs is they are only about 0.99 to 1.99 per 4 foot 
bulb ... very cheap. Anybody who tries to sell you anything else as 
'absolutely essential' is stringing you a line ... aquarium stores are 
the worst offenders with their 30 to 50 dollar bulbs.
Having said that, many people dont like the color of cool white bulbs. 
This, however, has NOTHING to do with the plants requirements but is 
simply personal taste. Also, if your plants wont flower under cool white 
light you might want to try something fancier. Finally, terrestrial 
plants are extremely sensitive to the red/far-red ratio (called the zeta 
ratio). Changes in the zeta ratio can completely alter the structure and 
growth of plants. Aquatic plants, however, are likely far less sensitive 
to the zeta ratio because of the rapid and variable attenuation of light 
in fresh waters. This means that the type of light aquatic plants receive 
is far less critical than for terrestrial plants.

Dr. dave


advantages and disadvantages of natural light

by George Booth <booth/hpmtlgb1.lvld.hp.com>
Date: Wed, 12 Nov 1997

> Uwe Behle and George got into a great discussion on this subject in
> that Krib URL I referenced above. Uwe says in the Aug 9, 93 article
> that it is suggested by H. J. Krause and Dennerle to have a dark
> period, either a noon dark period (Dennerle) or an entire dark day
> once a week (Krause). This is something new for all you folks battling
> algae to try!!
 
It was great until we both decided it didn't work AND it killed off all
my Rotala macrandra. I was doing a 2 hour dark period (4 on, 2 off, 6
on).  Good theory, bad practice.  Sorry. 


Re:

by George Booth <booth/hpmtlgb1.lvld.hp.com>
Date: Mon, 17 Nov 1997

> Date: Fri, 14 Nov 1997 23:59:11 -0800
> From: Stephen Pushak <teban-at-powersonic.bc.ca>

Sorry for any perceived peevishness here.  It's Monday.

> > It was great until we both decided it didn't work AND it killed off all
> > my Rotala macrandra. I was doing a 2 hour dark period (4 on, 2 off, 6
> > on).  Good theory, bad practice.  Sorry.
> 
> Do you have any theory on what happened to the R mac George? 

It didn't get enough light to grow very well and then it died.  

Or perhaps it started to grow really well in the morning 4 hour period,
then started to convert nutrients to sugars during the dark period,
then the sugar got carmelized during the next 6 hour light period and
clogged the plant's arteries.

Not being a botanist leaves me ill prepared to speculate on theories.

> How did the plants die?

Slowly and painfully. Leaves dropped off. Stems rotted. New leaves
didn't form.  

Again, I don't know because I didn't have an autopsy done.  This was a
very trying period for us since we lost a VERY robust strain of R.mac
that we had been shipping all over the country with great success.
And you know how well R.mac ships...

> Could your dark period have upset a diurnal rhythym of the plant? 

Either that or something else. 

> Preserving a low level of lighting during the dark period might
> prevent this. 

We had no way to do this on two of the tanks (their dual 2 bulb
fixtures were wired in parallel; something I'll NOT do again).
Another tank (with 2 175w MH and 2 40w Tritons on separate timers
suspended 14" above the tank) had what you describe but we didn't have
R.mac in that tank.

> This plant has fine roots which aren't well adapted to a low redox
> substrate however that probably wasn't the situation here.

I don't see the connection between a low redox substrate and a dark
period.  Less oxygen from the roots?  The tanks had heating cables.
Also, the R.mac roots weren't noticably finer than most other roots
such as R.indica, H.corymbosa, B.caroliniana, etc. The R.mac had
extremely robust and dense root structures that would regenerate in
two weeks after a top-off and replanting.

> If the overall light budget fell below the compensation threshold for
> Rotala macrandra, the plant could not produce sufficient sugars or
> energy reserves to sustain growth. This plant does require strong
> lighting.

That's my guess -- it didn't get enough light to grow very well and
then it died.  

> From your comment, I gather that you weren't able to observe a
> difference in algae growth?

That's correct. 

> As mentioned in the Krib article, green unicellular algae would be the
> most susceptible to this treatment.

We never had a problem with green water. 

> Filamentous algaes survive dark periods quite well. What types of
> algae were you testing?

The only visible algaes we were concerned with were red brush algae
and that green cottonball-like stuff that grows around fine
structured plants like E.tenellus <insert scientific names here>.

Neither were visibly affected. 

No scientific investigation was done.

Your results may vary. 

George in Colorado where the artic front has finally left

Green light

by eworobe/cc.UManitoba.CA
Date: Tue, 17 Mar 1998

As far as I know, green light is not a requirement for normal growth and 
is used much less efficiently than other wavelengths.
On another note, freshwater ecosystems do absorb light with fairly high 
extinction coefficients. Particulates, DOC, phytoplankton, zooplankton 
all absorb at particular wavelengths... the result is a light spectrum 
that is vastly different from incident radiation and one that is CHANGING 
all the time. IMHO this makes aquatic plants extremely well adapted to 
scavenging any and all PAR.

dave.


gro-lux, etc bulbs

by bae/cs.toronto.edu (Beverly Erlebacher)
Date: 23 Mar 98
Newsgroup: rec.aquaria.freshwater.plants

In article <3511F2BF.4EC0-at-nospam.powersonic.bc.ca>,
Steve Pushak  <teban-at-nospam.powersonic.bc.ca> wrote:
>Erik Olson wrote:
>> I always found Gro-Lux tubes to be as expensive as the aquarium types,
>> usually $15 or so.
>
>I think you can find cheaper FL bulbs for plants at Walmart or Canadian
>Tire. I don't know if you American types have Candian Tire stores there
>but you are welcome to come here to Canada where your money is worth
>LOTS!

In Ontario, at least, Cdn Tire has GE Sunshine bulbs on sale this week,
$5.99 marked down from $7.99, with a mail in mfr rebate of $2 makes $3.99
plus the cost of a stamp.  So it's a good time to try some out.  U.S.
readers, subtract 1/3 to get these amounts in U.S. $$.

>I _am_ kind of curious to hear if somebody knows one way or the other
>what the spectral response curve is for aquatic plants. That throws
>another factor into the watts vs lumens vs PAR debate but more from an
>academic point of view.

There's a book at the university library about aquatic plants that contains
a table summarizing growth reponse to light of various colors for several
fresh water plants and algae.  This is where I first read about the ability
of aquatic plants to use non-red non-blue wavelengths effectively.  If I
get the time to take the book out and type the numbers in, I'll post them.




Flourescent bulbs

by bae/cs.toronto.edu (Beverly Erlebacher)
Date: 3 Apr 98
Newsgroup: rec.aquaria.freshwater.misc

In article <35246ab9.14258200-at-news.earthlink.net>,
Leon Milberg <lmilberg-at-earthlink.net> wrote:
>Can anyone shed a little light :-) on the subject of fluorescent
>bulbs? I am talking about two pin, 48" bulbs on a ballast intended for
>40 watt. I would like to find information like:

Regarding your other posting, these are T12 (12/8 inch = 1.5 inch) 
standard tubes.  Until the past year or so, 90-95% of tube manufactured
in North America were 48" T12s.

>How is a bulb rated or specified for spectrum or color?
>What spectrum ratings apply to differing freshwater aquarium uses
>(i.e. plants, light sensitive fish, etc.)?

They are usually specified by use, except for certain specialty bulbs.
Cool white is the cheapest and is sort of general purpose, although
many people dislike the color which contains a lot of green.  Warm
white has more red in it and makes people's skins look healthier.  
Daylight is bluish.  Now there are names like GE's "Kitchen and Bath"
and "Plant and Aquarium", and Sylvania's "Gro Lux Wide Spectrum".

>Is there any research or documentation to support these
>differentiations, or is the information on experience?

I can't speak from experience about corals or reef tanks, but there
has been a lot of research done on light for plant growth.  Chlorophyll
absorbs mostly red and blue wavelengths.  However, plants have several
accessory pigments that can absorb other wavelengths and pass the energy
on to chlorophyll.  In actual practice, almost any reasonably intense
visible light will grow plants.  I've had excellent results with a 
combination of one cool white or daylight and one warm white or gro-lux
wide spectrum.  This gives a mixture of wavelengths that the plants
seem to like, and an apparent color that looks good to me.  GE now makes
a 5000k color temp tube called Chroma 50 or Sunshine.  People seem to 
have good luck with it, and it looks great.  Someone on one of these
groups did a spectral analysis and found that it closely resembles the
far more expensive Vitalite tubes by Phillips.

So the upshot is, common tubes from the hardware store can give you
great results in growing plants, and look good too, at a far lower
cost than special aquarium tubes.  It's more important to have adequate
amounts of light.  Two tubes the length of the tank will grow most 
common aquarium plants.  To have a really lush "Dutch aquarium" effect
you will need more light.  If the tank is 24" deep or more, you should
consider using metal halides if you want to grow medium or high light
requiring plants.

Light requirement is sometimes expressed by the fairly awful measure
watts per gallon.  At less than 1 watt per gallon you are restricted
to only a few kinds of plants with low light requirements.  2 watts
per gallon will grow most common plants.  For plants with high light
requirements or really heavy planting where the plants seriously shade
each other, you should have 3-4 watts per gallon.

I hope this helps.  The whole business of lighting and planted tanks
is very much a 90/10 thing - you can get 90% of the results with 10%
of the time/money/trouble, and the other 10% requires the other 90%.
So don't be afraid to start out with a simple and cheap set up and 
only upgrade if you can't get satisfactory results.




Lighting Fun

by krandall/world.std.com
Date: Mon, 01 Jun 1998

Michael D Nielsen wrote:

>I was just reading some of Karen Randall's stuff on Aquarium frontiers and
>ran across a point I would like clarified by anyone who really enjoys
>lighting nitpicking.
>
>Randall states that blue light produces bushy, short plants, something I
>have read many times in the past.  Thinking that I would like my plants to
>have this growth I have an Actinic 03 bulb on one of my tanks.  The plants
>look the same as in other non-actinic tanks.  Randall then states later
>that the actinic bulbs are not really necessary for the planted tanks and
>are more appropiate for the reefers.

Is this the only bulb you have on the tank?  If not, are you sure that the
single actinic bulb produces enough blue light to offset the light from the
other bulbs plus ambient light?  If so, have you seen the spectral curve
for your bulb?  Are you sure that other portions of the spectrum are not
adequately represented?

>This was one reason I included the blue bulb, but also because the blue
>light penetrates water better, thus getting to the substrate more.  Is the
>water penetration really of any importance?  Does anyone know the
>precentages lost in 24" (depth of tank to substrate)?

IMO, not enough that it makes any appreciable difference at aquarium
depths.  OTOH, Amano leans heavily toward green/blue lighting for his
tanks.  To each his/her own.<g>

>One final nitpick that I just want to mention is that Randall states that
>the VHO bulbs need special endcaps, have short lifes and run very hot.
>THis is true of the tar ballasts, but the electronic ballasts do not have
>these problems. 

> I have been using an Icecap 660 for 4 years with normal
>endcaps and bulb temperatures that are similar to the touch between the 4
>foot VHO and 4 foot normal.  Icecap also claims longer bulb life, but how
>can you judge that without accurate light meter equipment.

First of all, I didn't say anything about how hot or cool VHO's run.  I
said that they were similar in efficiency to NO fluorescents, and slightly
less efficient than MH's and energy efficient T-8's.  I have not seen
anything to make me believe this has changed.  

Second, I specifically said that the bulbs should be run on "special
ballasts" (meaning those specifically designed for VHO bulbs) for full
efficiency.  

It was my understanding that VHO's had a different pin arrangement than the
typical bi-pin NO or T-8 lamp.  Is this incorrect?   As far as bulb
degradation is concerned, the reports from other aquarists has been that
these bulbs generally require frequest replacement to avoid greatly
dimished light output.  If Icecap ballasts prevent that problem, that's a
great improvement.


Karen Randall
Aquatic Gardeners Association


Lighting Fun

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Mon, 1 Jun 1998

Michael Nielsen wrote:

>I was just reading some of Karen Randall's stuff on Aquarium frontiers and
>ran across a point I would like clarified by anyone who really enjoys
>lighting nitpicking.

If I'm responding, then that must be me.

>Randall states that blue light produces bushy, short plants, something I
>have read many times in the past.  Thinking that I would like my plants to
>have this growth I have an Actinic 03 bulb on one of my tanks.  The plants
>look the same as in other non-actinic tanks.  Randall then states later
>that the actinic bulbs are not really necessary for the planted tanks and
>are more appropiate for the reefers.

I can't say one way or another about the effect of blue light on the
morphology of aquatic plants.  As far as the use of actinic lighting goes,
I think this is something that creeped into plant keeping out of the reef
side of the hobby with no basis in plant husbandry.  It's just that the
one guy at the LFS who knows anything about lighting only really knows
about reefs and he gives the same recommendation to plant keepers that he
gives to coral keepers. 

>This was one reason I included the blue bulb, but also because the blue
>light penetrates water better, thus getting to the substrate more.  Is the
>water penetration really of any importance?  Does anyone know the
>precentages lost in 24" (depth of tank to substrate)?

This is extremely variable in fresh water.  How clear is your tank?  
There's also variables depending on the density and type of planting and 
a lot of odd details.  I think George and Karla Booth might measured some 
real numbers.  But ignoring all that...

Adey and Loveland (Table 1, p.117-118) list values that (converted from
meters) range from less than 2% per foot (Crater Lake, Oregon) to over
450% per foot (Lake George in Australia).  Just perusing their table I'd
guess that for nice, clear lake water something like 15% per foot might be
normal and adsorbtion over 30% per foot wouldn't be unusual. 

(This comes dangerously close to a "color of water in a white bucket"
discussion) ... The light at depth in fresh water (including our tanks)
probably isn't blue, because (again as Adey and Loveland point out) the
suspended particles and dissolved substances in fresh water do not adsorb
light like clear water or sea water.  The light at depth in freshwater
would be dim and yellow, red or brown - not blue except in the clearest of
freshwater lakes. 

Feel free to use actinic or other strongly blue light sources in your
aquarium, but probably you should do it for aesthetic reasons.  You
probably won't see a difference in the amount of light at the bottom of
your tank, you probably aren't simulating any plant-supporting freshwater
environment, and the plants you're growing might (or might not) respond to
blue light but they probably will not be dependent on a predominance of blue 
light in their environment. 


Roger Miller



Light and Node Distance

by krandall/world.std.com
Date: Thu, 02 Jul 1998

Michael Cordero wrote:

>hi all .. i would like to ask if light intensity, spectrum, etc
>would affect the way my stem plants grow .. meaning that how light
>affects node distance .. i think it was K randall who stated .. that
>more blue light makes the plant grow bushy and smaller leaves .. and
>shorter nodes .. i would like to establish that my stem plants have
>leaves with closely packed nodes this makes a few stalks look like
>a bunch of plants clumped together .. PLEASE COMMENT

>PS - correct me if im wrong karen

Thanks, I will.<g>  I did say that blue light promotes shorter, bushier
growth, while red light promotes taller, lankier growth.  This wasn't an
original statement on my part though, it's pretty well documented in
horticultural literature. I didn't say anything about leaf size.  The
trouble is that people have taken the above statement to mean that you can
(should?) emphasize one end of the spectrum over the other.  What I was
trying to get across (and obviously failed, since this has come up numerous
times<g>) is that with our present knowledge or lack thereof, it would seem
prudent to provide good balanced coverage at both ends of the spectrum.

As far as long internodes and small leaves, in my experience, this is most
likely a sign of inadequate intensity, rather than the "wrong" spectrum,
what ever that is.  Aquatic plants are remarkably adaptable, and live in a
_very_ complex environment.  It is tempting to make assumptions about cause
and effect, but unless the same response is seen by a large number of
people under a wide variety of "other" conditions (varying substrates,
nutrient supplementation, CO2 supplementation, plant species, etc) I would
hesitate to say that the ONE factor involved with any difference in growth
pattern is the specific spectrum used.

This is one of the reasons that "scientific" experiments are interesting,
but not always very useful for aquatic gardening.  The experiments are
usually done with a limited number of species, often not those commonly
used in aquaria, in very strictly controlled environments for relatively
short periods of time.  It's not that the finding are not valid, it's just
that there may be many other factors that can skew the results in the
working aquarium.

For instance, and I'm _NOT!!!_ suggesting that this is true... it is a
hypothetical example -

What if an experiment was set up to run for 60 days showing the effect of
red spectrum light and blue spectrum light over a specific plant.  At the
end of the 60 days, it is clear that the plants in the blue light are
shorter, but bushier.  What happens if you extend the blue only light
regime indefinitely?  Do those plants continue their growth pattern?  Do
they eventually dwarf themselves?  Is the fact that they are shorter a
response to spreading out under the blue light, or is it a sign that the
uptake of a specific mineral is being blocked, leading indirectly to the
shorter growth?  If you can isolate the mineral shortage, can it be
compensated for by adding more of this nutrient?

We don't know the answers to any of those questions.

It is good to discuss all this, and I think very helpful to share
experience.  But I think we need to be _very_ careful about drawing
conclusions.



Karen Randall
Aquatic Gardeners Association

Light Intensity vs Spectrum (long)

by Neil Frank <nfrank/mindspring.com>
Date: Wed, 01 Jul 1998

>Date: Tue, 30 Jun 1998 14:40:37 -0600 (MDT)
>From: George Booth <booth-at-lvld.hp.com>
>Subject: Re: Light Intensity vs Spectrum
>we are at 1.6 watts/gal so we may be "on the edge" as you put it and need
the 
>extra oomph of fresh bulbs.

I have 1.1 to 2.2 w/g in my large tanks. One 70g with 80w and the other
with 160w. (mix of tritons and grolux). Both energize the plants well (my
red plants are brilliant!), although the plants grow faster with 4 bulbs. I
also have a deeper 125 with 280w, but without fancy bulbs (a mix of 6-foot
growlux and daylight). The plants grow great and as fast as I can stand,
but the tank doesn't have that nice crisp blue-white look that the others
have, and the "red" plants (Rotala macrandra, Ludwegia sp.) do not get as
red until they are floating on the surface). Even my famous red horemanii
looses the dramatic red color and coverts to a pleasant but greener
apprearance (people who have visited my place need to comment because I am
red-green colorblind... but in my 70g tanks, my red plants really look red
..... even to me!!!)  Although the intensity may be a factor for the plants
at the bottom of the 22" deep 125g, it is the different spectrum that is
responsible for the difference in red pigment. (By the way, I can grow
Glossostigma elatnoides in the 125 and it does not grow vertical, so the
light intensity is more than adequate) 

For a given mix of bulbs, more intensity "may" be needed in some aquariums,
say with harder water. Some gardeners like Karen  Randall claim that they
need at least more 50% more light than me to grow some plants as well.
Apparently, this phenomenon is also the reason that hard water requires
higher concentrations of nutrients.  Karen: please comment if our
comparison of wattage considered the red spectrum (and blue) that my lights
provide.

>> Does it make sense that different spectrums of light can dramatically
affect
>> the color of plants? Tritons are a lot more red than cool whites. Maybe the
>> extra color is used by pigments other than chlorophyll?   
>
>I've always felt that the simplistic "plants don't need green light because 
>chlorophyll doesn't use it" and "plants are green because they don't adsorb 
>green light" was a bit too, um, simplistic.  In "Dynamic Aquaria", Dr. Adey 
>addresses the subject of accessory cells and other wavelengths of light. He 
>points out that more research needs to be done.

I agree with both points. At the NC State University, an agricultural
college, they have a phytotron..... a chamber to do growth studies of
plants. Guess what lights they use?
Cool white flourescent. Obviously, the plants know how to make good use of
the green light. NCSU's research has concluded that considering cost, they
can get their plants to grow just as well as with the "fancy" bulbs.  They
are not interested in how the plants look, just how they grow. I do not
recall if they studied flowering, so I can't comment on their conclusions. 

This is not to say that different spectrums are not more efficient watt for
watt. So, specialized bulbs are important when considering the need to
conserve space especially when it is easier to have 2 bulbs than 4... or
easier to have 4 than 6, 

Another interesting point about spectrum of bulbs is that for optimum
results they should not necessarily emulate the flat spectrum of sunlight.
First, natural light spectrum changes quite a bit depending on how it is
attenuated before it hits the plants. Clouds, particles, leaves and then
water humates (gilven), suspended algae, etc will change it dramatically.
For example, the light leaving the tree canopy of the jungle is rich in the
red end. 

Also, unfiltered flat spectrum sunlight may not be better. I recently
collected some Ludwegia palustris in South Carolina. Gorgeous red leaves
that rivaled my Rotala macrancra at its best. I set up a 55g peat bottom
tank (with a little soil covered with coarse sand) on my patio. It gets
eastern exposure, including a few hours of direct sunlight. I haven't yet
measured the light intensity, but I am betting it is brighter than any of
my indoor tanks. The results were disappointing!! The plant lost all of its
nice red color (otherwise, it has been growing nicely for approximately 2
months outside). I connected a yeast CO2 generator... this increased the
growth rate and got the plants to pearl... but  no change in color(not
surprising). The CO2 really made the collected chain swords really take
off!!(a wide leaf variety of tenellus that I have never prevously seen).
Last month I brought some Luwegia indoors and got it to regain most of its
original red brilliance in my 70g with the growlux/triton combination, but
NOT in the 125g. I am guessing that the peaty water of its native pond
absorbed much of the blue light and gave it a "natural" light heavily
weighted towards the reds. It would be great to have research to examine
the results of pigment production and growth rate as a function of color
AND intensity. They both need to be considered.  The spectral studies need
to consider bulbs with both blue, red and far red in different
combinations. Their effects on plants and on algae (G, BG, red, etc) are
needed. This may have already been done in Germany or elsewhere in Europe.
Please provide references, if known, so we can get them translated. 

- --Neil Frank, AGA
Translations of European literature provided to members of the AGA through
THE AQUATIC GARDENER

Making red plants really red

by Neil Frank <nfrank/mindspring.com>
Date: Thu, 02 Jul 1998

>From: "A. Inniss" <andrewi-at-u.washington.edu>

 I remember speculating, some time
>back, that _blue_ light was used more by red plants. 

My simplistic
>reasoning at the time was that red plants reflected more of the red end of
>the spectrum, so therefore they must use more of the blue spectrum. 

This speculation fits with my current experience with the collected
Ludwigia (now properly identified as L.repens). In the outdoor tank, it
gets morning sun which is a red light. The plant lost its red color. In the
tank with Triton/GrowLux mix... probably less intensity.... there is
proportionally more blue to its red... all the plants are a brilliant red.
[this is my "red" tank. It has Ludwegia species, E. horemanii-red, Ammania
senagalensis, Rotala macrandra, and a few green plants for balance <g>.
{anyone have any Eustralis stella for trade??)

Another supporting piece of evidence is that another interesting collected
plant - Gratiola ramonsa - has become very leggy (long internode distance)
in the patio tank. Another 'possible' indication of insufficient of blue.


 I had
>attributed the redness to the blueness of the light, but that was before I
>knew about anthocyanins, and before I'd read about Neil's Rotala
>macrandra, which was maroon in a 70 gal w/ a mere 80watts of light.

My 80 watts are a triton and gro-lux. Same light as the other tank above.
The macrandra is very similar!

Incidentally, I recently increased my carbonate and calcium/magnesium
hardness with crushed coral in filter and plants seem to love it.... no
change in colors.... only problem is the horemanii leaves are getting large
again (Ca was probably too low). The hardness does not seem to have
affected the colors... but remember, I am colorblind. :-)


re: DAWN TO DUSK LIGHTING

by "David W. Webb" <dwebb/ti.com>
Date: Tue, 22 Sep 1998
To: APD

>Date: Tue, 22 Sep 1998 17:33:36 +0800
>From: taburnok-at-skyinet.net
>Subject: DAWN TO DUSK LIGHTING
>
>hi all again .. i have a few questions bugging me .. and also some 
>ideas in for my new tank .. its a 5ftX24inX20inH .. i was planning
>some sort of light that has some sort of fluctuations in intensity
>something like dawn to dusk effect and sort of a cloud passing 
>by the sun and blocking it effect ..
>MY IDEA IS :
>
>1 40w 48in coralife trichromatic on at 830 am off at 1030 pm
>1 125w MV bulb rated at 4500K on at around 1030 am off at 830 pm
>1 125w MV bulb rated at 4500K on at around 1230 pm off at 530 pm
>1 40w 48in coralife trichromatic on at 100 pm off at 3-4 pm
>
>MV BULBS turn on and off at interchanging intervals most is 6times
>per day to simulate dark clouds

I tried complex lighting on-off patterns for about a year when I started
getting serious about plants.  I eventually decided that it wasn't
worthwhile.  The on-off intervals meant that my plants would stop
photosynthesis when the lights went off, but when they came back on, the
algae would get a jump on the plants as the plants churned up their
photosynthesis (or so it seemed to me, bottom line -- more algae grew).

Rotala sp don't do well with short lighting periods either.

You might get an interesting effect, but my recommendation would be to turn
it all on at once and run it all for 12 hours.

- --
David W. Webb  
Live-Foods list administrator

Darkness period and plant flowering

by krombhol/teclink.net (Paul Krombholz)
Date: Sat, 23 Jan 1999

>From: "ALEX PASTOR" <alexp@idirect.com>

>When I studied botany at university (many moons ago) we were taught that
>there are "short-day" and "long-day" plants.  Since that time this has all
>been overturned.  Quite recently, there was an article in the newspaper
>saying that there was no such thing, and that in fact it was the duration of
>the night period only that determines whether a particular plant will flower
>or not.  Apparently that is that.
>
>Dr. Momfish
>

The distinction between describing a plant as a short day plant  or a long
night plant is not important as long as the plant is on a 24 hour cycle.
If it gets short days, it will automatically get long nights.  The
distinction was made because it was found that plants measure the night
length, not the day length.  There is a pigment in plants called
phytochrome that exists in two forms, phytochrome red (P660) and
phytochorme far red (P700).  Plants begin their nights with most of the
pigment in the P700 form, which slowly converts to P660 during the night.
The amount converted is the measure of the night length.

P660 absorbs red light, with a peak absorbance at a wavelength of 660
micrometers. When P660 absorbs red light, it converts to P700.  P700
absorbs far red light, with a peak absorbance at 700 micrometers.  When
P700 absorbs far red light, it converts back to P660.  Daylight has a lot
more red light than far red light, and that is why the plant starts off its
night with mostly P700, the form that slowly reverts to P660.  A short day
(long night) plant needs a long night to accumulate enough P660 to trigger
the hormonal sequence that leads to blooming.  If the night is too short,
P660 does not build up to high enough levels to trigger blooming.  The two
phytochromes are quite sensitive to light, and even room lighting has
enough red light to keep the 'clock' from running, i.e., keep any P660 from
building up.  Even the relatively dim light from street lights has enough
red light to slow down the clock and give plants the "misinformation" that
the night is a lot shorter than it really is.  Every November I see weeds
growing near street lights that delayed blooming and got killed by the
frosts while still in the vegetative state.  Further away from the lights,
the weeds have gone to seed in plenty of time.

Steve Pushiak mentioned on Jan. 22 that his Ocelot sword bloomed after he
had been on vacation for a week.  While the house was unoccupied, there
were no room lights on after dark to prevent the clock from running, and
the plant got the long nights required for blooming.  Room light strong
enough to keep the clock from running is not strong enough for any
meaningful photosynthesis.

"Normal" light that plants are likely to encounter has much more red than
far red light, and so the effect is always to reset the clock to the point
where nearly all the phytochrome is in the P700 form.  With just a brief
flash of red light in the middle of a long night, the clock will be reset,
and the plant starts counting from the beginning.  With a special filter
that only allows far red light through, it is possible, with a flash of far
red light, to run the clock to the end and create the effect of a long
night.


Paul Krombholz, in cloudy, chilly, central Mississippi


Ozelot sword flowering

by Dave Gomberg <gomberg/wcf.com>
Date: Sun, 24 Jan 1999

At 03:48 AM 1/24/99 -0500, Olga Betts said:

> I have an ozelot sword  and it flowers in my tank under ordinary
conditions...by that
>I mean... I don't change anything to make it flower. It gets 12 hours of
>tank light plus several hours of "room" light both natural and incadescent.
>I don't believe the person who grew these ozelots and who continues to grow
>them, does anything special with light.

More on ozelot sword flowering:  I decided to see what warm feet would do
for my tank, so I put a 60w lamp under it (in the stand).   A week later my
ozelot sent up a flower stalk.

- --
Dave Gomberg, San Francisco            mailto:gomberg@wcf.com
http://www.wcf.com/co2iron
- -----------------------------------------------------------------


Watts/lumens (again?)

by "David W. Webb" <dwebb/ti.com>
Date: Fri, 22 Jan 1999

> From: IDMiamiBob@aol.com
> 
> Okay, guys, help me out here.  When we talk about two watts per gallon, 
> are we talking standard florescents?  <snip> But re we talking two 40-watt 
> bulbs without decent reflectors?  Or are we talking about light fixture 
> bulbs without bulbs without of 50%.  

The guidelines have been around for a while, and I'm trying now to define
something I didn't originate, so what I say is open for debate.

In this case, the rule of thumb is that two watts per gallon of pretty much
any type of fluorescent lighting will be sufficient for the large majority
of plants.  Of course, I'm not considering UV tubes or anything that 
exotic.  Within the rule of thumb, reflectors aren't really considered, so
you can easily use your two watts per gallon and by improving your 
reflector, you can get more PAR (photosynthetically active radiation) and
lumens (visible radiation) into the tank where your plants and eyes can 
use it.

> And then what happens when we go to the local lighting store and find 
> Philips ultralumes, which are visibly way brighter than standard bulbs?  
> Or are wealready talking about the enhanced output bulbs when we say 
> that we have two watts per gallon?

Since plants seem able to use wavelengths across the visible spectra, 
additional brightness out of a tube probably help them that much more.
But, when we say we have two watts per gallon, we say nothing about the
quality of the light.  We're just saying two watts of fluorescent 
lighting per gallon.  

The nice thing about aquariums is that if you can stand the way the tank
looks and have at least that much lighting, you're probably doing pretty
good for your plants.  This 'probably' is the basis for the two watts per
gallon rule of thumb. 

> Okay, I know that this is just a rule of thumb to simplify our tank 
> planning and layout.  Yet I read numerous discussions here about 
> alkalinity, pH, ferrous compounds, EDTA, etc. ad infinitum which seem to 
> get really really detailed, certainly more detailed than most of us need 
> to get a handle on the basics.  

With each of the factors that you mention, there are a bunch of different 
ways to get the desired results, and for that matter, there are a range of
results that may fit the term 'desired', depending on the aquarist's goals
for aquatic husbandry.  Lighting plays into this as well.  With 2w/g, you 
probably won't kill most of your plants due to lack of lighting.  Some may
not do as well as others, and some may die, but they may die for reasons
other than lighting.

Here are a few considerations that come to mind that directly affect 
the amount of light that arrives at the plants, but are not addressed by 
the rule of thumb:

Lumen output of the lights
CRI of the lights
PAR of the lights
Lighting blends
Light reflectors
Focusing reflectors
Reflective loss due to cover glass or plastic
Reflective loss due to the surface of the water
Proximity of lights to plants
Submersed vs. emersed growth
Reflective gain for emersed growth due to the surface of the water
Attenuation due to cover glass or plastic
Turbitity of water
Depth of tank
Light piping effect
Glass vs. plastic aquarium
Algae on plants
Algae on glass
Density of plants
Substrate color and reflectivity

> Now I want some more guidelines.  I have 
> three tritons over my 30 gallon tank.  They look twice as bright as the 
> bulbs that came with the strip lights, so do they count as 60 watts each?  
> I am setting up my 55 to have one F40/T12-75UL, one F40/T10-50AX, and two 
> Interpet Triton 40 watters.  All ofthese bulbs are way brighter than the 
> standard F40/T12 bulbs. Am I overkilling it?  And do you know of a website
> for Philips or Interpet where the lumens ratings for these bulbs are 
> posted?  Or an address I can write to?

In my estimation, you are probably doing just fine.  The rule of thumb gives
you an average minimum to start with.  You can go up from there, and it
looks like you are.  My favorite lights are the PennPlax Ultra Trilux.  I 
like these because of their brightness and color (bluish-violet).  They mix 
well with Tritons (more purplish) and cost about the same.  Having said 
that, I personally don't have enough money to go buying either Ultra Trilux 
or Tritons, so I go with GE Chroma 50's, 75's, CW, and PL/AQ blends.

I think that in order to know what you desire, you need to measure PAR and 
lumens at the plants in different parts of your tank  I have neither a PAR
meter nor a lumens/lux meter, so I just tend to start with the rule of thumb
and then tailor my lighting to meet my goals for each tank.

I know I didn't answer all of your questions, but I hope this helps,

- -- 
David W. Webb
Live-Foods list administrator


Aquatic Plants Digest V3 #795

by Michael Dubinovsky <mikluha/ix.netcom.com>
Date: Fri, 22 Jan 1999

>Date: Fri, 22 Jan 1999 09:01:05 PST
>From: "Colin Anderson" <colin_d_anderson@hotmail.com>
>Subject: Chroma 50 and 'Plant Bulbs'
>
>Sorry, but I can't resist.  Why would we use 'plant' light bulbs?  IF 
>LUMENS are in your equation at all...

>
>
>You bought the ballast, the fixture, whatever, paid your dues, now GO 
>FOR THE LUMENS!  If anyone would like to refute the arguement that 
>nearly all light grows plants and that more lumens are better, I'd like 
>to hear it :~>
>
Ok, you're asking for it.

Why don't you consider green laser. It has maximal possible lumen per watt
value. By definition 1 watt at 555 hm equals to 683 Lm. But, I don't think
plants would like this light.
To find lumen-per-watt value at any other wave-length you need to multiply
watts by human eye photopic response curve. Lumen value is lamp parameter
that tells how "bright" this lamp appears to human eye (we actually see
brightness, not lumen flux, but this is a different story). For, example
sun has about 100 LPW (and balckbody at 5500K, too). This can be calculated
by multiplying balck body spectral radiant poower curve by eye response.
So, lumens are useless if you talk about light that are used for other than
illumination for human eye purposes. Even more, the human has different
(scotopic) response curve at darkness. For, example, if you take red and
dark blue color, red appears brighter for than blue, but in dark room, blue
seems to be brighter.
Thus, if lamp is optimized for use with plant grow (it has two peaks at
blue and red and no or small green), then it has very low LPW. 20W Philips
Agro-Lite produce only 600 initial lumens. And average 20W fluorescent
lamp - around 1200-1600 Lm. You need to use PAR values or simply power in
watts in each spectral region. And you don't need to go for lumens. You
need lumens to illuminate plants/fishes so you can them well. You need
lumens only for you. FOr plants you need energy. 
Next - CRI. CRI is charateristic of color rendering, the ability to
represent color of objects. 
To calcultae CRI you need to compare the lamp and test-source. For example,
CRI of usual incandescent lamp is 100 (for source <5000K, test source is
special incandescent lamp, for source >5000K it is "dyalight" source). SO,
you can't even compare CRI of two lamps if they have different CCT.  
Nothing comes free. Higher CRI means less lumens. Comapre LPW of typical
TL90 and TL80 lamp. Color rendering is important for human eye only. Plant
lamps have very poor CRI (they have no green, so they can't represent green
colors). But plants don't care about CRI. You care, because you want your
plants/fish look natural (what does natural look mean?).
CCT - same problem. Lamp color can be described by it chromatiicity, two
color coordinates - 'x' and 'y'. You may wish to check any good
photomtery/color book/Inet site to look at color triangle. This two
parameters define completely color of lamp. But, we don't like two numbers.
We want one (so, companies can promote their lamps - 5000K, 10000K,
20000K...it's difficult to say what is better x=0.434, y=0.356 or x=0.465,
y=0.324). So, CCT was introduced. This is temperature of blackbody that has
closest chromaticity. Actually, it doesn't say how close. You can make lamp
with CCT=100000 very easily. Just stick blue filter before incandescent
lamp. Two lamps with same CCT may have different colors. Basically, as
higher CCT (after 5500K) as lower LPW. This is because balckbody at
5000-6000K has maximal LPW - our eye is optimized to sun spectrum.

Finally, as long as your lamp has blue and red (that measn higher PAR
value), plants gonna like it. Even combination of daylight (it has blue)
and incandencent (or low CCT ceramlux lamp) will work OK.  You need high
CRI lamps for you, not for plants (yes, high CRI lamps has blue and red,
it's necessesary to get high CRI, and plants like them).

About, gettins twice more lumens/energy from lamp. Even aquarium keeper
should remeber about energy conservation law. If you put 4 lamps with
1500Lm (or 150 w) each, you never (I even don't like hear if anyone
disagree:) can get more lumens, by using reflectors. You can try to recycle
light and shift its frequency toward green and gain more lumens per watt,
but this is different story. Why people tell that reflector help get more
light. It's easy. When catalog says that lamp produce 1500 LM, this means
light goes in all directions. You need light that goes in certain direction
(down). So up-going light is lost for you. You can use less than 50% of
light without reflectors. Lets' say you place lamp 6 from water surface and
tank is 12" wide. Only light within 90 degree angle is used = 25% of light.
Only 375 Lm hits the water. Even less light reaches the bottom. You can use
reflector. Good ALZAK aluminum reflector has reflectance of 90-95%. Nickel
reflector98%, but it costs $$$$$$$$ Cheap foil probably has 80%
reflectance. By placing foil above lamp you can redirect 20% more light (so
you get twice more light at water surface). By using special designed
reflector you can collect about 60-70% of lamp light. Maybe even more - I
should play with numbers on my computer - I would use kind of shallow
parabolic or shape similar to big 'M' letter. With more than one lamp
reflector efficiency drops, because lamps blocks light. BTW, this can cause
lamp overheating and drop in light output and life. The optimal solution
would be use of aperture lamps. I saw these lamps in catalogs, but never in
store.






>This data is from the krib, take a look at:
>
>http://www.thekrib.com/Lights/fluorescent-table.html
>
>Thank-you,

Take a look at:

www.philipslighting.com - they put recently catalogs and information
literature on their homepage.
www.lightingresource.com
www.osram.com
www.ge.com and so on


>
>Colin Anderson         
>
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail.com
>


Michael, who makes his living by designing weird shit around weird lamps.


lighting small tanks, watts per gallon rule? (long)

by Wright Huntley <huntley1/home.com>
Date: Mon, 15 Mar 1999

> Date: Sun, 14 Mar 1999 20:53:45 -0500
> From: "wayne jones" <waj@MNSi.Net>
> 
> One of the things that really bugs me is spectral charts for individual lamps.
> They never have any meaningful units so you cannot use them to compare one lamp
> against another. If manufacturers would simply publish charts plotting watts or
> lumens or einsteins/m2 versus frequency one could easily determine what lamp
> produces the most PAR. Then we could have a formula of PAR/gallon. I can't even
> get meaningful information on lamps that are specifically designed for aquarium
> use.

C'mon guys. One more time. 

Power spectrum is (relative) Watts vs inverse frequency (or wavelength). All the
lamp outfits use that standard format.

It *can't* be expressed in "lumens" vs frequency, for lumens -- by definition --
have a particular spectrum built in. That spectrum is the viewing sensitivity of
the "standard observer." [A human eye thing.] It's 10 times higher in green than
in either blue or red. Plants usually reflect away green, absorb red strongly,
and blue somewhat less. Lumens *inverts* what we usually want for optimum plant
growth.

PAR is only a bit better, for it assumes a wider spectrum, but rarely does it
agree very well with the action spectrum of *your* particular plants, anyway.
Again, no such thing as PAR vs frequency. Same reason.

Einsteins count photons, and photons have different energy at different
wavelenths, so a "spectrum" of Einsteins vs frequency would have the frequency
squared and look pretty strange if not totally useless.

Bob Dixon had commented: 

> >But with the high variablity in lumens per watt these days, that still doesn't
> >really tell us anything.  

Wrong. It gives us an excellent *indirect* clue. The good tubes that have lower
lumens/Watt are usually putting more energy in the ends of the spectrum where
plants are more growth active, and less in the more visible green region. Tubes
with high lumens/Watt will make the tank *look* brighter, but "feed" the plants
less.

[One glaring exception is some of the poorly-designed fish-shop tubes. They have
lower lumens per Watt because they are just poor designs with unstable
phosphors. They often even lose substantial brightness as they age, unlike all
good tubes that retain up to 90% until they will not even fire any more.]

Just mix and match to get the combo of plant growth and appearance that you
like. I have one 55G with two GE "P&A" tubes and a "cool white" for a total of
120W. The plants grow quickly (for no CO2) and the tank looks nice. If I turn
off the cw, it dies visually. It "looks" like I turned off way more than half
the light!

> >Yes, PAR would be eeven more effective still, but that is hard
> >to detirmine based on the available info for the different types of bulbs.

Read the spectra as *relative* Watts vs inverse frequency (or wavelength) The
peak is normalized to one, and all other values are just a percentage of that.
[Yes, it *is* frustrating that they assume you know that and never, ever label
the vertical axis.]

For pleasing your eye, look for lots of energy (area under the curve) in the
green-yellow region (500-600nm) and for your plants look for plenty in the deep
red (700nm) and near blue (450nm) regions. 

CRI can tell how "white" the light looks, but is useless when mixing tubes. Two
with CRI lower than 80 can have a combined CRI of nearly 100.

Color Temperature is also an "appearance" scale, and is fairly worthless. I lean
toward the 3000K range for plant performance and the 5000-6000K range for
appearance, if that's all I have to go by. Anything much higher than 6500K may
tend to look too harsh and glaringly blue. It may also lack the red that plants
prefer.

In summary, you still need about 2W/G for good viewing and good growth. If you
go higher, you will probably be CO2 limited. Mix tubes to balance viewing
pleasure and plant growth. Deep, narrow tanks may need less light than that, due
to light-pipe effect. [The rule of thumb assumes the "normal" tank dimensions.]

It's not rocket science, so don't *try* to get too numerically accurate. You'll
just get frustrated. Watch your plants to see what works best for you.

Wright

- -- 
Wright Huntley, Fremont CA, USA, 510 494-8679  huntley1 at home dot com

One big difference between a Libertarian and a Demopublican is the 
Libertarian knows it's not a waste to vote against a Republocrat. 
                   http://www.self-gov.org/


watts vs. lumens

by Wright Huntley <huntley1/home.com>
Date: Mon, 15 Mar 1999

> Date: Mon, 15 Mar 1999 20:16:38 +0100
> From: "Ole Larsen" <olet@larsen.dk>
> Subject: watts vs. lumens

snip..
> 
> Sorry, I donĀ“t know the expression PAR

Photosynthetically Active Radiation. Sounds really nice, but has only a little
more meaning than lumens, IMHO. It is defined in terms of the recipient, and not
the source of radiation. Unfortunately, the defined "plant" it isn't our usual
recipients, aquatic plants and people. ;-)

> Lumens is a measure of what comes out as light ( candela/steradian) and thus
> better, but far from good enough

This statement is quite misleading, and lies at the heart of a lot of the
misinformation we encounter here on the APD. Lumen is a psychophysical term that
describes the way *humans* perceive optical radiation. Candela is a member of
that same photometric system. They are defined in terms of the human observer,
and not the source radiation. They tell you next to nothing about what actually
"comes out."

Here in APD we define light in a much broader sense, usually. Lumens *are* great
for predicting how bright the light will "look." Too many lumens per Watt always
cheats the plants out of energy *they* need, for the manufacturers of "cool
white" tubes have gotten really very good at not wasting red and blue light we
don't see well, anyway.

Red and blue are about 20% of the output of a very high lumens/Watt tube.
Unfortunately they are about 80% of the photosynthetically active spectrum of
our plants. That's why plants *can* grow well under "cool white" lights. You
just may need several times as many Watts of it.

Wright

- -- 
Wright Huntley, Fremont CA, USA, 510 494-8679  huntley1 at home dot com

One big difference between a Libertarian and a Demopublican is the 
Libertarian knows it's not a waste to vote against a Republocrat. 
                   http://www.self-gov.org/


watts vs. lumens

by busko/stsci.edu (Ivo Busko)
Date: Tue, 16 Mar 1999

Regarding the discussion about lumens/Watts/PAR/etc. you techies on
the list can look at

http://www.cs.indiana.edu/hyplan/kuzimmer/IES/section3.2.html

Lumens are units of luminous flux, and this quantity is defined based
on an integral over wavelength or frequency. Thus the assertion that
"For any given freqency lumens can can be converted to either watts or
PAR values" is meaningless. Lumens cannot be computed in any given
infinitesimal frequency/wavelength interval, but only in a finite range
of frequency/wavelength. Thus a spectral plot can never have lumens
in the vertical axis.

To translate the relative units used by lamp manufacturers into Watts
one first have to compute the integral under the spectral curve. One
could copy the curve onto graph paper and estimate the area by counting
squares. This total area S (in units such as inches X nanometers) 
corresponds to the lamp output in Watts P thus one just have to multiply
the vertical axis by P/S to get the lamp spectrum in Watts/nm. Of course,
this assumes 100% conversion efficiency. Following the same principles one 
could also multiply this spectrum by the photopic curve (e.g. in
http://www.reefnet.on.ca/gearbag/wwwlux.html)
and compute the integral to get the lamp output in lumens. Comparison
of this figure with the manufacturer's published lumen rating for the
lamp should give an idea of the conversion efficiency.

The same procedure could be used with a photosynthesis action spectrum
in place of the photopic curve. This would give the lamp output in
PAR units instead of lumens. 

- -Ivo Busko
 Baltimore, MD


RE: PAR, Lumens, Watts, etc

by busko/stsci.edu (Ivo Busko)
Date: Mon, 22 Mar 1999

The recent thread on PAR/lumens/watts prompted me to pursue a small
project I was thinking about. When selecting fluorescent bulbs for my
planted aquarium, I couldn't find any consistent quantitative info to 
use as selection criteria (besides price...). I had spectral plots
and lumen specs, but how these translate into PAR and other pertinent
measures ? Being limited by space above the tank (and money) to 2 watt/gal, 
I wanted to have the most bang for my watts. But with the spectral plot,
lumen and watt rating for a bulb, it is possible to derive such
measures. I already sketched the principles in a former posting, but after
that post I realized that I had at my fingertips all the resources to carry 
out the project: just a computer and the appropriate software. 

The basic idea is that, from the manufacturer's published bulb spectrum 
(in relative units) and the bulb's published lumen output and electrical
power consumption, we can in principle compute other bulb parameters such
as PAR output.

For carrying out the comparisons, I used only spectral curves and bulb data
I was able to get from the web, as well as some web-published photosynthesis 
action spectra. I can send/post the data sources if requested. I also had
to write a short computer program to carry out the computations.

I got data just for NO fluorescents, since this is the type of bulb in
which I'm interested. But the methodology is general and applicable to 
*any* light source.

For people interested in this, I can send a detailed description of the
computation steps, as well as a discussion of possible error sources
(they would make this posting too long). If anyone has access to spectral
curves of bulbs not listed in here, I'll appreciate to get a pointer to them.

The columns in the table list the following quantities:

Power: the bulb's rated power.

Maximum lumen output; this theoretical value depends only on the bulb's
spectrum and rated power. It is the lumen output that the bulb would have
if all electrical energy input to the bulb were transformed into luminous
energy.

Rated lumens: (initial) taken from bulb's specs, except the Triton and P&A,
which are educated guesses.

Efficiency: the ratio between rated lumens and maximum lumens. I was a bit
surprised by the low values. How manufacturers compute fluorescent bulb
efficiencies ? I was expecting values in the range of 0.3-0.5.

PAR: the bulb's output in PAR. The units are just photons/sec, I don't
know what are the appropriate units in which to express PAR measures.
But these figures are OK as far as *relative* comparisons go.

MPAR: Modified PAR (this was the main goal of the experiment !). There has
been some suggestions to use a photosynthesis action spectrum to weight 
the PAR measure, in the same way as the eye's photopic response is used to
weight the lumen measure. This is exactly what I did here, using an "average" 
action spectrum curve. The "total" column lists the sum of all photons in the 
range 400-700nm. But since there are no clues in these figures about the 
*relative* amount of red and blue photons, I also computed MPAR in the 
400-500 nm range only (blue) and 600-700 nm range only (red). R/B is just 
the ratio between the red and blue MPARs.


Bulb        Power   Max.   Rated   Effic.  PAR          MPAR         R/B
             (W)   lumens  lumens                 total  blue  red

                                               (1.E15 phot./sec)

Triton        40    8000   2200    0.28    170    105    68    23    0.34
AX50          40   12000   3600    0.30    200    100    48    36    0.75
PowerGlo      40    8500   2200    0.26    160    100    58    22    0.38
AquaGlo       40    4800    960    0.20    140     94    35    52    1.50
GroLux        40    5900   1200    0.20    140     87    26    53    2.05
SP65          40   11700   3050    0.26    170     87    43    24    0.57
Daylight Dlx. 40   10400   2550    0.25    160     83    39    25    0.65
C50           40    9900   2250    0.23    160     76    26    34    1.32
SunGlo        40   13400   3100    0.23    150     72    31    19    0.61
P&A           40    9200   1900    0.21    150     70    15    42    2.90
FloraGlo      40   12500   2180    0.17    120     57     9    33    3.77
TL950         32   12500   2000    0.16     90     34     8    10    1.23


The table lists the bulbs in decreasing MPAR order. It is roughly also the
PAR decreasing order, but not quite so. But I think the most interesting
result is the blue/red comparison. There is a hint of a correlation of
R/B with MPAR output, in the sense that the highest MPAR bulbs are also
the bluest, and the ones with the least production of PAR photons are also
the reddest. Thus very high PAR (or MPAR) output shouldn't be the only
criterion when seeking for the optimum bulb, if the goal is to have also
a good balance between red and blue.

It is easy, from this data, to compute figures for multi/mixed bulb
configurations, by just adding the individual bulb's measures, weighted
by the number of bulbs of each type in the mix. So it should be easy to 
come up with optimum mixes given the constraints of ones' configuration. 

And bear in mind: these results are only as good as the manufacturer's 
published spectral curves allow them to be. Some curves seem to be quite
accurate and have adequate spectral resolution (AX50, SP65, Daylight Deluxe). 
Others have somewhat less detail (TL950, P&A, C50), and others are grossly 
smoothed out (the Hagen "Glo" bulbs). I estimate that erors should be a few
percent for the best data, up to 10-15 percent in the absolute values 
(much less in R/B) for the worst ones.

And just wondering: why lumens are defined in terms of energy while
PARs are defined in terms of photons ? Are the processes acting in
the eye not driven by photons, as photosynthesis is ?

- -Ivo Busko
 Baltimore, MD


PAR, Lumens, Watts, etc

by Michael Dubinovsky <mikluha/ix.netcom.com>
Date: Wed, 17 Mar 1999

Here is data from "Proceedings International Lighting in Controlled
Environmets Workshop" 1994. Gerald Deitzer - "Spectral comparison of
sunlight and different lamps"

He gives two tables.  First is the spectral distribution for various lamps
sources. All of the values are normalized to 100 mkmol /(m^2*s) of PAR
(400-700 nm). Percetange are ampounts of photons relative to sunlight

                    UV            Blue   Green     Red     Far Red
Lamp+Barrier  250-350  350-400 400-500 500-600  600-700   700-750

Sun             2.88     6.21    29.16   35.20    35.64     17.00
   
Incandes.        0       0.47    7.52    28.49    63.98     47.00
100W + 1/8"               7%      26%     81%      180%      276% 
plexiglass

Cool White       0.03    1.11    24.85   52.59    22.56     1.40
1/8" plex.       1%      18%      85%    149%      63%       8%

Vita-Lite        0.54    2.32    26.31   40.69    33.0      7.0
                 19%     37%      90%     116%     90%       40%

Gro-Lux          0.16    3.72    29.36    20.22   50.42     1.01 
(original)        6%      60%     101%    57%      141%     6%

Gro-lux          0       0.83    19.78    32.52   47.70     10.00        
(Wide spectrum)           13%      68%     92%     134%     59%
+1/8" plex.

Cool WHite+      0.02    1.03    22.63    49.22   28.15     8
incandescent      1%      17%      78%     140%    79%      47%
(100W)
in a 1:3 ratio
+ 1/8" plex



all other lamps - HPS, Xenon, LED, etc.



Table 2 provides amount of energy in W/m^2 relative to number of photons of
PAR (400-700 nm) for each lamp. ALso, it allows to calculate illumination
level if you know PAR (mk mol /(m^2*s)). 

                  PAR/(W/m^2 per mkmol/(m^2*s))  Lux per PAR (mkmol/(m^2*s)) 
Sunlight                    0.22                        55.18     

Incandescent+1/8" plex      0.20                        49.00

Cool WHite + 1/8" plex      0.22                        78.75

Vita-Lite                   0.22                        62.78
 
Gro-Lux original            0.22                        37.02

Gro-Lux                     0.21                        55.09
(wide spectrum)+1/8" plex    

Microwave+1/4" plex         0.22                        67.43

CoolWHite+
100W Incandes.              0.21                        74.53
(1:3 ratio) + 1/8" plex



So.......cheap Gro-Lux is the same as expensive Vita-Lite (even better in
blue and red regions). And combination of CW+incandescent is good also (you
can find similar data in Philips Lighting Handbook)


Enjoy. 


Michael, who design wierd shit around wierd lamps for living


PAR, Lumens, Watts, etc

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Wed, 17 Mar 1999

On Wed, 17 Mar 1999, Michael Dubinovsky wrote:

> Here is data from "Proceedings International Lighting in Controlled
> Environmets Workshop" 1994. Gerald Deitzer - "Spectral comparison of
> sunlight and different lamps"

Great info, Mike.  Thanks.

[snip]

> Table 2 provides amount of energy in W/m^2 relative to number of photons of
> PAR (400-700 nm) for each lamp. ALso, it allows to calculate illumination
> level if you know PAR (mk mol /(m^2*s)).
>
>                   PAR/(W/m^2 per mkmol/(m^2*s))  Lux per PAR (mkmol/(m^2*s))
> Sunlight                    0.22                        55.18
>
> Incandescent+1/8" plex      0.20                        49.00
>
> Cool WHite + 1/8" plex      0.22                        78.75
>
> Vita-Lite                   0.22                        62.78
>
> Gro-Lux original            0.22                        37.02
>
> Gro-Lux                     0.21                        55.09
> (wide spectrum)+1/8" plex
>
> Microwave+1/4" plex         0.22                        67.43
>
> CoolWHite+
> 100W Incandes.              0.21                        74.53
> (1:3 ratio) + 1/8" plex
>
>
>
> So.......cheap Gro-Lux is the same as expensive Vita-Lite (even better in
> blue and red regions). And combination of CW+incandescent is good also (you
> can find similar data in Philips Lighting Handbook)

Well, maybe not.  It looks to me like the column on the left shows that at
the same PAR, the vitalite will appear much brighter than the gro-lux
(higher Lux/PAR - Lux is lumens/square meter).  In fact CW+incandescent
would be about twice as bright as the gro-lux, and CW alone would be more
than twice as bright, even though they're all producing the same PAR.
This is another illustration that lumens (or lux) are a poor measure for
judging the quality of light for growing plants.

Roger Miller


Potassium and CF Lighting

by Michael Dubinovsky <mikluha/ix.netcom.com>
Date: Sun, 14 Nov 1999

>Date: Fri, 12 Nov 1999 11:21:34 -0800
>From: "Dixon, Steven T. (Exchange)" <stdixon@ben.bechtel.com>
>Subject: Potassium and CF Lighting
>
>While I'm at it let me offer up an observation I've been meaning to post for
>a while, and ask a question about CF lighting.
>
>
>Am I right in recalling that PAR ratings would give us a rating which would
>better correlate with plants general ability to use light than lumens?

You need to know the spectrum. Lumens correlate with human eye. Basically,
it's a source energy spectrum mulplied by photopic curve (=standard eye
sensivity  curve). 
PAR is a just number of photons. Photoosynthesis is a quantum process, i.e.
all  photons produce equal effect regardless of their energy. Quantum yield
(=is the moles of carbon fixed per mole of photons absorbed) curve is
practically constant in 400-700 nm range (check, fro example, Taiz, Zeiger
Plant Physiology, 1991). As one can see, equal amount of energy of "red"
light  produces more PAR photons then same amount of energy of "blue" light.
Unfortunately, uniforme quantum yeild deosn't say anything about overall
ability plant to use light. It only says that if photon get absorbed by
plant it's used with 100% efficiency. But not every photon get absorbed.
Thus, you need to know chloroplast absorption spectrum and how well it
corellates to lamp spectrum. Otherwise, both lumens and PAR are senseless.
Green laser is the most efficent light source. It produce almost 700 lm/W
(1 W = 683 Lm at 555 nm). It produces certaing amount of PAR photons.
However, plants have poor absorptions in green region (that's why we see
plants green). So using a green laser with certain amount of lumen and PAR
gives completely different result than using  different power lamp but same
amount of lumens or PAR. 
I'd say that the best unit of measure would be something similar to lumens
with using average plant absorption curve instead of eye curve. I never saw
such units, but this is used, for example, for estimation of efficiency of
UV lamp. Lamp spectrum is multiplied by "bacterial" responce. 
Next problem. Above will give you corellation with the plant
photosynthesis. But, different part of spectrum produce different effect in
plants - different growth, different vegetaion period, different
productivity (most of studies were conducted with "useful" plants - tomato,
cuccmber, not anubias or crypts. If one can get something from crypts, then
they will be object of research). For example, productivity of tomato
(fruit yiled) is maximal then most energy is in red part of spectrum
                PAR %                                     Average daily 
400 - 500 nm       500 - 600 nm     600 - 700 nm       fruit yields (g/m^3)
    60               20                 20                 100 +/-7
    20               40                 40                 141 +/-8
    10               15                 75                 185 +/-12  

(from  Proceedings of International Lighting in Controlled Environments
Workshop)
if you look into maximal plants growth size, then you need different
spectrum and so on.

Therefore, you can't judge source only by its lumen/par/watt value.



>
>A few weeks ago Michael Rubin sent me a copy of a note from Erik Olson
>which, if I paraphrase correctly, essentially stated that CF lights are not
>in fact more efficient, that they do not put out more light per watt than
>normal fluorescent bulbs.  I do not recall if Erik was referring to lumen or
>PAR output.  One of Erik's points was that the technology of the two types
>of bulbs was more or less the same--however it is that these bulbs actually
>work.
>
>Just to make a stupid observation of my own, all seem to agree that the new
>T-8 bulbs are more efficient, which I take to mean that T-8 bulbs put out
>more light per watt (again, I'm not sure if we mean lumens or PAR when this
>is said) than the old T-12 bulbs.  So perhaps simply saying that all of
>these bulbs use the same technology doesn't really answer the efficiency
>question.
>
>Does anyone have a definitive answer to this question?  Do CF bulbs put out
>more light per watt (lumen or PAR) than regular fluorescent bulbs; than T-8
>bulbs?  Do we have data on this point?
>
>Thanks for you views, and apologies for my use of the bandwidth today.
>
>Regards, Steve Dixon  San Francisco
>


Check www.philipslighting.com, www.sylvania.com, ge - probably -
www.gelighting.com
They have all catalogs containing all lumen output, so you can calculate by
yourself.
To compare apples to apples you need to note (when you compare lamps of the
same power)
1) lamps with different CCT (corellated color temperature) have different
lumen output.  Cool white lamp has the most efficiency
2) In general, lamp wirh high CRI (color rendering index) value has less
lumen output. To get higher CRI lamp spectrum must be "wider" and this
results lower efficiency
3) lamp using ballast with higher ballast factor produce more lumens.
Modern electronic ballasts have ballast factor of 1.0-1.2. ALso,
high-frequency operation increase performance, too.
4) higher power lamps have better efficiency (less "shipping and handling"
losses). For example, 1 40W lamp deliver more light then 2 20W lamps.

Here are some data from Sylvania catalog

Compact Fl. lamp (Dulux-L), 40W, T5, CCT=4100K, CRI=82, length=22.6",
Initial lumens=3150
Similar lamp - 55W - 4800Lm

Pentron High output T-5 39W, 36" 4100K, CRI=82, 3500 Lm

Octron 700 series lamp 40W, T-8, 60" length, CCT=4100K, CRI=75, 3550 Lm,
Octron 800 series lamp 40W, T-8, 60" length, CCT=4100K, CRI=82, 3775 Lm,

Standard rapid start lamp - 40W, 48", 4100K, 3200 Lm
Gro-Lux 40W, 48" - 1200 Lm

if you check european catalog at Philips, Osram-Sylvania sites, you will be
moire impressed by quality of their lamps. In US energy costs nothing
compared to Europe, so nobody cares about light quality and efficiency. 

As you can see, T-8 is more efficient. T-5 has same efficiency as T8. T12 -
sucks. Compact fluorescent has less efficiency then T5/T8.....but, don't
forget that they compact. Both tubes block each other. I don't have a
software with me now  to estimate light loss, but I can do it tomorrow. I
think bended T-5/T-8 would yeild same efficiency as compact fluorescent


Mike,
who design wierd optics around weird lamps


CF Lighting Recommendations Needed

by busko/stsci.edu (Ivo Busko)
Date: Fri, 30 Jul 1999

This is a follow-up of my older post at 

http://www.actwin.com/fish/aquatic-plants/month.9903/msg00462.html

In that article I show a quantitative comparison of fluorescent bulbs with
emphasis on plant use. Since them I augmented the database with the
inclusion of more bulb data, including one power compact fluorescent 
(Osram/Sylvania Dulux 5400K) and one metal halide (Iwasaki 6500K). 

Here is the new complete table, arranged in decreasing order of PAR
output. See the former article for explanations.


Bulb        Power   Max.   Rated   Effic.  PAR          MPAR         R/B
             (W)   lumens  lumens                 total  blue  red

                                              (1.E15 phot./sec)

Iwasaki65    175   45000  12000    0.27   123.     60.9  26.1  20.4  0.78
Dulux540      55   16000   4800    0.30    42.9    21.1  11.8   5.7  0.48
AX50          40   12000   3600    0.30    31.6    15.5   7.7   5.2  0.68
Triton        40    8000   2200    0.28    27.3    16.4  10.9   3.5  0.32
SP65          40   11700   3050    0.26    26.4    13.5   6.9   3.7  0.53
PowerGlo      40    8500   2200    0.26    25.7    15.8   9.3   3.5  0.37
Daylight Dlx. 40   10400   2550    0.25    25.5    13.2   6.3   4.0  0.64
C50           40    9900   2250    0.23    24.7    12.1   4.1   5.4  1.30
SunGlo        40   13400   3100    0.23    23.9    11.3   5.0   2.8  0.57
Perfecto      40    7300   1600    0.22    23.4    14.4   5.1   7.5  1.47
P&A           40    9200   1900    0.21    23.4    11.1   2.3   6.7  2.88
Osram Biolux  40   10800   2400    0.22    22.5    12.2   5.5   3.1  0.53
GroLux        40    5900   1200    0.20    22.3    14.0   4.2   8.6  2.05
AquaGlo       40    4800    960    0.20    21.4    15.0   5.6   8.4  1.49
FloraGlo      40   12500   2180    0.17    19.2     8.8   1.4   5.1  3.57
TL950         32   12500   2000    0.16    13.4     5.5   1.3   1.5  1.17
Ott CF        23    5400   1200    0.22    12.9     7.6   3.9   2.4  0.62

(Thanks to Roger Miller for identifying an error in the conversion to
photons/sec, and for providing a nice photopic curve and software)

For the two bulbs of interest:

                  Lumens/watt    PAR/watt    MPAR/watt

Iwasaki 6500          69          0.70         0.35
Dulux 5400            87          0.78         0.38


The lumens/watt and MPAR/watt measures are sensitive to the particular
spectral distribution created by each bulb, but the PAR/watt is not.
The evidence suggests that CFs can have the same efficiency, or even
be slightly more efficient than MHs, although this can only be said for 
sure for the two bulbs analyzed here. The Iwasaki spectrum looks better,
from a plant viewpoint, than the Dulux's triphospor spectrum, though. 

- -Ivo Busko
 Baltimore, MD


CF Lighting Recommendations Needed

by busko/stsci.edu (Ivo Busko)
Date: Fri, 30 Jul 1999

In my former post there is a small error: the power consumption of the
Iwasaki 6500K bulb is not 175 watt but 150 watt. The error is in the
database that was used to compute the table and affects both the bulb 
efficiency factor and the lumens/watt figure. The revised values are:

efficiency:   0.31
lumens/watt:  80

The conclusions are still valid though.

Tanks to Victor Eng for pointing out the error !

- -Ivo Busko
 Baltimore, MD


halogen lights

by busko/stsci.edu (Ivo Busko)
Date: Thu, 12 Aug 1999

>>> Do you know the PAR
>>> rating?
> 
>Why don't you humour me and just tell me
>the PAR rating of the lamp if you know
>it.

Some hard data to settle (or stir up) the discussion: a typical narrow-beam
60 watt halogen spot (Philips Masterline Par 16 (60PAR16/H/NSP) dumps
208 footcandles in a 12.7" diameter spot at 6 feet, according to the
data sheet at

http://www.lighting.philips.com/nam/prodinfo/halogen/p3254.shtml)

This translates to about 730 lumens. The color temperature is 2950K and
the spectrum is a perfect Planck curve. Thus we can readily compute the total 
photon flux in the 400-700 nm range, it is 1.28 10^16 photons/sec, or
about 2.13 10^14 photons/sec/watt. A typical high-efficiency tri-phospor
normal fluorescent creates about 7.9 10^14 phot/s/watt in the same 
wavelength range, and a typical plant light (grolux) 5.6 10^14 phot/s/watt. 
So the three bulbs have PAR efficiencies that scale as 1 : 3.7 : 2.6 for 
halogen : tri-phospor : grolux respectively. Of course these ratios are
valid only in the case where the fluorescent tubes are mounted under
"perfect" reflectors, at least as efficient as the built-in halogen
bulb reflector. If a "typical" fluorescent fixture reflector has an 
efficiency of 50% (I think I saw a figure like this in the krib archives)
the ratios would be 1 : 1.85 : 1.3 instead. Not too bad for the halogen,
if one's willing to live with that extremely narrow bean. A wider bean
halogen (50PAR20/H/NFL30) disperses the same amout of light over a 10 
times larger area.

Btw, the power conversion efficiency of the halogen bulb (emited watts
divided by input watts) is only about 0.07.

<snip>

>>> In plant growing Lumens/watt can
>>> be used to measure system
>efficiencies
>>> but has almost no bearing on the PAR
>>> rating of the lamp.
>
>>That's a strong statement. They are
>very *closely* correlated for most
>>lights, and only really come apart for
>lights whose spectrum has been
>>efficiently tailored to human scotopic
>sensitivity -- for example, CW
>>fluorescents.

More hard data: the correlation coefficient I get from 17 bulb types
(between lumen/watt and PAR/watt) is 0.64, suggesting that hardly any
correlation exists. In fact only 3 out of the 17 bulbs show a systematic
trend (high PAR/watt *and* lumen/watt), the remaining 13 show very 
similar values of PAR/watt (within a factor 25%) but lumen/watt values 
ranging from 20 to 80, a factor 4 (or 300%). The correlation coefficient 
for these 13 bulbs is 0.38, suggesting in fact that no correlation exists 
for most bulb types.

- -Ivo Busko
 Baltimore




 


Potassium and CF Lighting (CF vs T5)

by Michael Dubinovsky <mikluha/ix.netcom.com>
Date: Tue, 16 Nov 1999

>Here are some data from Sylvania catalog
>
>Compact Fl. lamp (Dulux-L), 40W, T5, CCT=4100K, CRI=82, length=22.6",
Initial >lumens=3150
>Similar lamp - 55W - 4800Lm
>
>Pentron High output T-5 39W, 36" 4100K, CRI=82, 3500 Lm
>
>Octron 700 series lamp 40W, T-8, 60" length, CCT=4100K, CRI=75, 3550 Lm,
>Octron 800 series lamp 40W, T-8, 60" length, CCT=4100K, CRI=82, 3775 Lm,
>
>
>As you can see, T-8 is more efficient. T-5 has same efficiency as T8. T12
- - >sucks. Compact fluorescent has less efficiency then T5/T8.....but, don't
>forget that they compact. Both tubes block each other. I don't have a
software >with me now  to estimate light loss, but I can do it tomorrow. I
think bended >T-5/T-8 would yeild same efficiency as compact fluorescent
>


Addition:

I spent some time on computer. Efficiency of bended T5 tube (or two T5
tubes) placed at distance of 0.2-0.3" apart equals to 87-89%. This gives
(T5/T8 = 3500-3800 Lm) for PC output: 3050 - 3300 Lm (exactly as catalog
value). Therefore, lower lumen output in case of Power Compact can be
explained by blocking light by each tube. E-mail me, if you need details.




Mike,
who design wierd optics around weird lamps


Ligthing

by busko/stsci.edu (Ivo Busko)
Date: Fri, 14 Jul 2000

Wright Huntley <huntley1@home.com> wrote:

<snip>
> There is *no* effective attenuation of the photosynthetically active
> spectrum in clear tanks that are less than a few *meters* deep. If you
<snip>

Not quite so. I converted the curves published at
http://www.aquabotanic.com/paper2-6.html from their standard 1m depth to a
"typical" aquarium depth of 16". For pure water, absorption at the blue end
(400-500 nm) is effectively zero. But for all other cases: pure water at the
red end (600-700 nm), and water with a reasonable amount of organics, 
absorption is in the range 20-50%. Significant IMO. Of course, this should 
affect mostly low lying plants. Stem plants and large swords for instance, 
should see less of the effect.

- - Ivo Busko
  Baltimore, MD

 


Watts and hogwash

by Wright Huntley <huntley1/home.com>
Date: Thu, 13 Jul 2000

The 2W/G rule of thumb is based on several assumptions -- all true. It is
still just a rough guide. The trick is to work on the things you can
control. The better you do them, the less W/G you may need for good growth.

It assumes adequacy in other nutrients and that they are "well balanced."
;-)

It assumes reasonable spectrum in the fluorescent (or MH) lamps, with lower
lumens often an indication of better spectrum (less high-visibility green
and more red and blue for better photosynthesis). [Some really bad lamps are
in the trade, but the big names like GE and Phillips have gotten very, very
good at getting high efficiency out of the phosphors for the entire life of
the tube. Typically about 90% of average when the tube no longer fires at
all.]

It assumes a fairly normal tank shape. [Extra long or tall hex tanks
probably need somewhat less W/G.]

I see several folks out there gagging on my last paragraph above. :-) It is
well-entrenched aquarium mythology that deeper tanks need more light to
"penetrate" to the bottom. That's pure hogwash, unless you have such dense
blackwater the back is hard to even see. Your plants would really look lousy
in any tank with *any* significant depth attenuation.

There is *no* effective attenuation of the photosynthetically active
spectrum in clear tanks that are less than a few *meters* deep. If you
really *do* need more light, it is because of the way your plants are
arranged, with big swords shadowing hairgrass, gloss. etc., or a *lot* of
algae on the glass absorbing/scattering the internal reflections. Arranging
plantings for low-light plants, like Anubias, to be in shade is something I
think I've heard Karen expound on. It's the cheapest increase in effective
light you can buy.

In free space, radiation falls off in intensity as the inverse square of the
distance from a limited source (point).

The tank is not free space, and your lamps -- even MH -- are not point
sources. Light that you manage to get coupled into the tank through the top
surface stays inside, like a light pipe, until it encounters some
absorbing/refecting surface. 

If that surface is light-colored gravel, it may be mostly lost out into the
room. If it is plants, much green is lost, but much of the rest of the
spectrum is absorbed and used for photosynthesis. BTW, anything you can
actually *see* in the tank is from light not being used by the plants!

Essentially, what you need is enough light to properly illuminate the
planted acreage you have. Tall tanks need less light, per gallon, and low,
wide tanks need more, all other things being equal. 2W/G, efficiently
coupled, will raise most plants very well in standard-shaped tanks. 

Surface loss at the water is minimal (typically about 10% under normal, low
high-reflective hoods) unless you let it overgrow with Riccia, duckweed,
etc. Likewise the losses of cover glasses are negligible (<10%) if kept even
moderately clean. Don't worry about it.

The experts using the lower light levels have all paid close attention to
the following.

Get the light as close to the surface as possible for other reasons.
Spillover is truly expensive. It rarely adds to the aesthetics, too, unless
you need the room light.

Skinny fluorescent tubes are more efficient at generating light than fat
ones. Going from 1.5" (T12) tubes to 1" (T8) is an improvement, with CF
being even better. Skinny tubes also permit design of more efficient
reflectors, so restrike losses are reduced, and angle of incidence of most
light is more vertical at the surface. [Grazing incidence light is somewhat
more reflected away from the surface or cover and wasted.]

Any dark colors inside the hood are serious sources of loss. Bright white
exterior paint is very good, but coated mylar and coated aluminum can be a
lot better with skinny tubes. [See the AH Supply web pages for more on this.
http://ahsupply.com/36,40,or.htm ] Plain aluminum is fair in blue and UV,
but absorbs up to 15% or more of the most useful photoactive spectrum in
green, red and near-IR. Nevertheless, I have a lot of commercial hoods lined
with household aluminum foil -- it beats that black or brown plastic hands
down!

Look to the design of the inside of your hoods or plantings to get the
required W/G down, and quit worrying about stuff that does not matter, like
depth and surface losses. <g>

Free advice is worth every cent, too. <VBG>

Wright

- -- 
Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com

           To err is human. To blame someone else is politics.
               *** http://www.self-gov.org/index.html ***


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