You are at The Krib ->Plants ->Misc. Tech [E-mail]

Light Spectrum and Color Temperature

Contents:

  1. Bulbs/Far Red Light
    by krandall-at-world.std.com (Karen A Randall) (Thu, 8 Feb 1996)
  2. RE: Color spectrum Vs Degree Kelvin??
    by AllenKAgX-at-aol.com (Sat, 18 Jan 1997)
  3. Halogen spots
    by "Richard J. Sexton" <richard/aquaria.net> (Tue, 1 Dec 1998)
  4. Halogen Spots&Costco Halogens
    by "A. Inniss" <andrewi/u.washington.edu> (Tue, 1 Dec 1998)
  5. RE: Light Spectrum
    by "James Purchase" <jpurch/interlog.com> (Tue, 15 Dec 1998)
  6. GE light alternatives
    by "Roger S. Miller" <rgrmill/rt66.com> (Thu, 21 Jan 1999)
  7. "Sunlight" vs "A/P" tubes
    by Wright Huntley <huntley1/home.com> (Thu, 21 Jan 1999)
  8. GE Chroma vs Super Daylight
    by SnoTabby/aol.com (Fri, 22 Jan 1999)
  9. fluorescent tubes
    by "Richard J. Sexton" <richard/aquaria.net> (Fri, 22 Jan 1999)
  10. Watts/lumens (again?)
    by Wright Huntley <huntley1/home.com> (Fri, 22 Jan 1999)
  11. Watts/lumens (again?)
    by "Roger S. Miller" <rgrmill/rt66.com> (Fri, 22 Jan 1999)
  12. flourescent tubes
    by "Roger S. Miller" <rgrmill/rt66.com> (Fri, 22 Jan 1999)
  13. Aquatic Plants Digest V3 #798
    by "Richard J. Sexton" <richard/aquaria.net> (Sat, 23 Jan 1999)
  14. Aquatic Plants Digest V4 #407
    by "II, Thomas Barr" <tcbiii/earthlink.net> (Thu, 13 Jul 2000)
  15. Dutch aquarium lighting
    by busko/stsci.edu (Ivo Busko) (Mon, 11 Dec 2000)
  16. Aquatic Plants Digest V4 #712
    by Lennart =?iso-8859-1?Q?Ed=E9n?= <le.e/privat.utfors.se> (Tue, 12 Dec 2000)
  17. Dutch aquarium lighting
    by busko/stsci.edu (Ivo Busko) (Tue, 12 Dec 2000)
  18. light attenuation
    by "Roger S. Miller" <rgrmill/rt66.com> (Mon, 17 Jul 2000)
  19. Aquatic Plants Digest V4 #609
    by busko/stsci.edu (Ivo Busko) (Mon, 16 Oct 2000)

Bulbs/Far Red Light

by krandall-at-world.std.com (Karen A Randall)
Date: Thu, 8 Feb 1996

 Subject: Bulbs/Far Red End?

> The only concern I have about the G
> Aquarium bulb is that it says on the package that unlike other b
> produces a relatively high emission of far-red radiation that pr
> and flowering of many types of plants.  I think I read here on t
> the far-red spectrum can be bad for aquarium plants and possibly
> growth.  Anyone know anything about this?  

According to "Biology of Plants" by Peter H. Raven and Helena 
Curtis, while red light promotes plant growth, far red light turns 
it off like a switch.  Experiments were done where if the the far 
red light was turned off last, the plants would stop growing 
completely. (until the next light period)  These _were_ 
terrestrial plants, though, not aquatics.  I guess they use this 
principle to control the growth and flowering of various flowering 
plants offered commercially so they all come into bloom at the 
same (chosen) time.

- ------------------------------

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA

RE: Color spectrum Vs Degree Kelvin??

by AllenKAgX-at-aol.com
Date: Sat, 18 Jan 1997

First of all thanks Miles, I've been lurking and learning for several months,
and finally someone asked a question that falls in my area of expertise
(Imaging and photo sci.)
You asked:

>>I was wondering if any or our resident technophiles could help me 
understand the relationship between the color spectrum of light as 
measured by nanometers vs. degrees Kelvin. <<

The Kelvin rating (the term degrees is not used) is a color index that is
derived by heating a black body (a Carbon instrument). As the black body is
heated it glows and emits light. EG. at 3,000 K the black body emits a very
red orange light (similar the color of your standard houshold tungsten
filament bulb). At 9,000 K the black body is emitting a very blue light
(similar to the light reflected off of a blue sky). And by the way it's very
hot!

The color spectrum refers to the content of the emitted light accross all the
visible light wavelengths. Many light sources are full spectrum. They are
emiting light at every wavelength in the visible light spectrum. For example
a tungsten bulb is full spectrum, but it emits more in the red area of the
spectrum than in the blue or green, thus the lower Kelvin rating. A Xennon
arc (electronic flash tube) is full spectrum but emits more light in the blue
and green than the red, and usually has a high Kelvin rating, 9,000 -10,000
Kelvin if they are not filtered.

Many light sources emit only a band, spikes or a narrow range in the visible
light spectrum. Helium Lasers emit a very narrow spectrum (620nm???). In a
graph of the visible light spectrum the Helium laser registers as a single
line or wavelength. 

Flourescent Bulbs produce light by exciting phosphors. There are many
phosphors with a varying spectral charateristics. The standard office cool
white emits little to no light in the red region. The majority of the light
is emitted in the green spectrum because our eyes are more sensitive to
green. Hey they look brighter! If you were to look at a graph of the visible
light spectrum the cool white bulbs have a large spike in the green region
and some smaller spikes in the blue and only negligible stuff in the red. Our
eyes (brain) compensates for the color shift. Nor  does we notice the missing
spectrum since we only have single wavelength red, green and blue receptors.
Manufactures can pick phospors to create different color ratings. For full
spectrum bulbs they add red emitting phosphors to the mix, but the bulbs
still have missing some wavelengths and they have spikes in other areas (Red,
Green & Blue). 

>> Is it possible to say I have a 5000k light which corresponds to a certain 
wavelength of light as measured in nanometers or is degrees Kelvin a 
combination of spectrums as I would assume it would have to be if a 5000k 
bulb is considered a full spectrum bulb.<<

No, the 5,000 Kelvin does not refer to a certain wavelength but the color
resulting from the mix of wavelengths. For example a Tungsten light can be
filtered and or burned hotter to create the 5,000 K color and it is full
spectrum. A flourescent bulb could have just three phosphors a red, green and
blue one to acheive a 5,000 K color. You can evalutuate the quality of the
flourescent bulbs by their CRI (Color Rendering Index). A bulb that has a
high CRI generally has a good number of and mixture of phosphors.

FYI, Infrared and Ultraviolet are not classified as light on the
electromagnetic spectrum.

Hope this helps.

Ken Allen
Lexington, MA.


Halogen spots

by "Richard J. Sexton" <richard/aquaria.net>
Date: Tue, 1 Dec 1998

At 03:48 AM 11/29/98 -0500, Aquatic Plants Digest wrote:
>Supposing the above observations hold.  Then how to explain this.  No one
>has "proved" that 3000K incandescents don't do an exceptional job of
>driving chlorophylls, have they?  Maybe the incandescent has just the right
>spectrum.  And maybe the problems with controlling heat explain why
>historically incandescent hasn't been favored.   Quartz tubes can run MUCH
>hotter, so that innovation may lead to high illumination densities.  

In _Lighting for Plant Growth_ the authors demonstrated
the absorbtion spectra for chloraphyll an designed a light
to provide optimal output spectra, matched to that curve.

The modern day "Gro Lux" type fluorescent tube was the
result. Those dim dark purple things eevrybody scoffs
at. Wide spectrum Grow Lux came later and is more of a pink
than a purple; the output spectra was widened up so
the peaks of red and blue were not so sharp.

Actually, the original Gro Lux tube was not exactly
what the researchers described, rather, it was a compromise
to contemporary manufacturing techniqes are morso the
extreme cost of the phosphour that makes red.

So, two things spring to mind: 

 1) If matching the output spectra to the chlorophyll
abosrbtion specta is the rught thing to do, why don't
we use gro lux exclusivly. Could it be that plants do
better with a spectra that is not the same as what 
chlorophyll requires ? For example, could infrared
prehaps speed up the photosynthic cycle by incresaing the
temperature and lowering activation energies ?

 2) Note what was missing in the original Gro Lux
because of cost: the red comnponent. I'm a string
believer in incandescent suppliments to fluorescent
lighting and am to an extent almost convinced
Swords do better under this than just fluorescent.
If you look at the output spectra of an incandescent
bulb, it's like a right angled triangle, massive
near red, lots of red, diminishing to nothing near
yellow.

So, no, it wouldn't surprise me in the least if halogen
spots grew great plants. You might want to add one of the
(now cheap) Chroma 50's ($6 CDN in the local automotive
chain, ya gotta love it) to suppliment blue though.


- --
Richard J. Sexton                                         richard@aquaria.net
Maitland House, Bannockburn, Ontario, Canada, K0K 1Y0       +1 (613) 473 1719



Halogen Spots&Costco Halogens

by "A. Inniss" <andrewi/u.washington.edu>
Date: Tue, 1 Dec 1998

Richard Sexton mentions that he believes incandescent/halogen lighting can
be great for plant growth.  I agree completely,especially, as Richard
mentioned, for Swords.  In fact, it has been rumoured that Mike Trznkowski
grows/used to grow his Swords under incandescent.

I had intended to include little halogen spots on a 40gal tank onc, but
was too lazy to go out ond do it.   I intend to try it on the 75 I will
(eventually) set up -- especially if I can find the type of set-up Dave
described.  If I go for this, I'll let the list know how it goes.

			Andrew

~^~
 ~



RE: Light Spectrum

by "James Purchase" <jpurch/interlog.com>
Date: Tue, 15 Dec 1998

Paul Westall asked, in APD #711:

> question about flourescent bulbs.  I have read that "most" aquarium =
> plants prefer a buld with color temp less than 5300-5400K.  But, many =
> people on the list seem to have great success with higher temp, bluer, =
> bulbs.  In the past I have used 5500K metal halide which seemed to work =
> well.  Do you think that 6500K flourescent bulbs are too blue for most =
> freshwater plants?  Or, how about a mix of Chroma50 and Chroma 75?

Paul, this is only _my_ opinion, based upon my _own_ experience with plants
and different light sources. When I first started with the hobby (a long,
long time ago) I used incandescents (2X60W over a 15Gal tank), and I was
able to grow plants. Not very well, mind you, but they did grow - especially
Crypts.

Over the years, I have tried _most_ of the commonly available fluorescent
tubes (except HO and VHO) as well as 5500K Metal Halides. My experience has
been that provided your give them ENOUGH light, it doesn't really matter
that you use a specific spectrum bulb. Perhaps if you were trying to get
African violets to bloom, the spectrum might make a big difference, but in
an aquarium we are looking (generally) for vegetative growth and if there is
a high enough level of _any_ kind of light, the plants will grow.

I would suggest, that for all practical purposes, in a typical aquarium in a
living room, it is more important to get a bulb or a mixture of bulbs which
is pleasing to YOUR eyes. Different tubes provide a slightly different
"color" of light. You can see this if you see lighted tubes of different
types side by side. Chroma 50's are great, and they seem to have become more
easily available in recent years, therefore they are cheap too. Chroma 75's
are a little "bluer" (to my eye, anyway) but it still "looks" white. A
mixture of the two would be fine for plants.

What you DON'T need to do is spend mega bucks on $30.00 "aquarium tubes"
that are marketed by a number of companies. I like to get a bulb with a high
CRI (Color Rendering Index - Sunlight is rated at 100, Chroma 50's are 90,
Chroma 75's are 92) and a Color Temp. of at least 5,000K. That way, I know
that it will look natural to my eye, provide a full specrum of light (or a
close approximation of a full spectrum) to the plants, and not cost me an
arm and a leg.

James Purchase
Toronto



GE light alternatives

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Thu, 21 Jan 1999

Pete Rose wrote:

> I've got a question:
> At our local Target, they sell both GE "sunlight" bulbs and GE
> aquarium/plant bulbs for the same price.
> Which is better? I was guessing the plant bulbs, but I've seen the
> sunlight bulbs recommended a couple of times. Thanks.

Either one will grow plants, so it comes down to a question of which you
would rather view the plants with.  I think most people find the light
from a GE PL/AQ bulb to be not to their liking.  I find it rather yellow
and other people may have other descriptions.  The "sunlight" bulb
produces what I perceive as white light.  I have sunlight bulbs
side-by-side with much more expensive vitalites and I can't detect much
difference between their colors.


Roger Miller


"Sunlight" vs "A/P" tubes

by Wright Huntley <huntley1/home.com>
Date: Thu, 21 Jan 1999

> Date: Thu, 21 Jan 1999 10:25:23 -0800 (PST)
> From: pete rose <bfordyce@yahoo.com>
> Subject: Re: Aquatic Plants Digest V3 #790

snip...

> I've got a question:
> At our local Target, they sell both GE "sunlight" bulbs and GE
> aquarium/plant bulbs for the same price.
> Which is better? I was guessing the plant bulbs, but I've seen the
> sunlight bulbs recommended a couple of times. Thanks.

If the "sunlight" are Chroma 50 o/e, they will grow plants well, but
look a bit dim and a tiny bit too orange for best viewing. I put a
couple of the "Plant and Aquariums" (40W) above a newly set up 55G and
the tank really looked dim. They have so much energy nearly out of the
visible spectrum that they need a *lot* of Watts for comfortable viewing
(i.e., to get the lumens up). Otherwise, they look to me to be pretty
white, but just a tad magenta or purplish in color.

I added one "cool white" and it was as if I had quadrupled the
illumination. The tank has a lot of irridescent fish, and the plants and
fish just became dazzling.

The "P/A" tubes probably provide plenty of plant energy, and the "cool
white" lots of viewing light. The trick is to get a nice balance that
grows plants and also looks good. Since plants and eyes have different
response spectra, I always seem to be happier mixing different tubes to
get the results I want.

Another favorite combo of mine is one "Chroma 50" and one "daylight."
80W over a 55G T is clearly limited by CO2, and not by photons. [Add CO2
and watch bubbles appear and growth explode.]

Wright

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

Liberalism is totalitarianism with a human face.
                                  Thomas Sowell


GE Chroma vs Super Daylight

by SnoTabby/aol.com
Date: Fri, 22 Jan 1999

I've used both bulbs in combination and alone. The Chroma 50's give me more
compact growth compared to their "Super Daylights".

I haven't yet figured out why, because the "Super Daylights" put out more
lumens and a whiter light. Could the less compact growth of stem plants be due
to the difference in spectrum? I was under the impression from reading this
list, and other information, that spectrum isn't as important as the total
output of lumens. 

I like the color better when I mix them, 2 Supers/3 Chromas. The Chromas alone
give off an odd tint, though not totally unpleasant. Right now it's 5 Chromas
over the tank, and the growth of the stem plants is quite nice and compact.

Susan

In a message dated 1/21/99 8:49:47 PM, Aquatic-Plants-Owner@actwin.com writes:

<<> Look for a red box and the words "Chroma 50" on the tube. I think
> they sell them as "Super Daylight".
> 

I've got a question:
At our local Target, they sell both GE "sunlight" bulbs and GE
aquarium/plant bulbs for the same price.
Which is better? I was guessing the plant bulbs, but I've seen the
sunlight bulbs recommended a couple of times. Thanks.>>


fluorescent tubes

by "Richard J. Sexton" <richard/aquaria.net>
Date: Fri, 22 Jan 1999

I'm seeing a bunch of statements here about fluorescent tubes
that leave me shaking my head.

"Plant and aquarium" tubes are gro-lux wide spectrum. They're pink,
not yellow or orange. Regular gro lux is purple.

They have huge spikes in the red and blue ends of the spetrum, 
almost no yellow or green and do not put out any energy in
non-visible ends of the spectrum. The cri is something like 65;
cri just means how close tosunlight it *appears* to the human
eye and has nothing todo with how well it will grow plants.

Chroma 50's emulate sunlight. The CRI should be a lot higher than
the numbers I've seen mentioned here. The C50 simulates noon
day equitorial sunlight. The C75 emulates noon day northern
sunlight.

I can't imagine what would make poeple think C50's or PL-AQ's
look "yellow" or "orange". A warm white might give you this 
impression, but a C50 has a decidely blue tinge to it, and the
PLAQ's are quite pink.

I think some of you people are color blind! :-)


- --
Richard J. Sexton                                         richard@aquaria.net
Maitland House, Bannockburn, Ontario, Canada, K0K 1Y0       +1 (613) 473 1719


Watts/lumens (again?)

by Wright Huntley <huntley1/home.com>
Date: Fri, 22 Jan 1999

> 
> Date: Thu, 21 Jan 1999 20:17:21 EST
> From: IDMiamiBob@aol.com
> Subject: Watts/lumens (again?)

Bob Dixon wrote

> 
> Okay, guys, help me out here.  When we talk about two watts per gallon, are we
> talking standard florescents?  

Not "cool white" but any reasonably wide-spectrum tube with modestly
efficient phosphors.


> By standard I mean those 3180 lumens 40 watt
> tubes that come standard on most light fixtures and are sold in grocery store
> everywhere.  They offer 79 lumens per watt, or thereabouts.

Sounds like "cool white" or "CW."  

Forget lumens, or look for *lower* lumens per Watt! Your *eye* is what
determines lumens (a psychophysical term). It is 10 times more sensitive
to green than to blue or red. Plants, OTOH, are about 2-5 times more
able to use red (or blue) than green, which they often reflect away. The
combined effect means a tube must spread energy outside the human
response curve for best plant growth, usually. That always results in
lower lumens/Watt. [Bad phosphors also give low lumens/Watt so stick to
the major brands to be safe. Many lfs tubes are just poor and die
quickly.]

Somewhere in the archives there is a pair of curves I did on this a
couple of years ago. A repost would be in order if some kind soul has it
handy.

>  But re we talking two 40-watt bulbs without
> decent reflectors?  Or are we talking about light fixture with a reflectivity
> of 50%.  Or are we required to get something like "Coilzak", which has an 89%
> reflectivity minimum guarantee?  If I use a highly reflective fixture, can I
> say that I have inceased those 158 lumens by 90%, because all the light that
> was going up instead of down is now heading properly into the tank?  Which
> would put me at 300 lumens per gallon.

I think we assume reasonable reflectors in the rule-of-thumb. As I
stated recently, I get lack of CO2 as the limiting factor with 80W over
a tall 55G. That's with a good white reflector, as provided in a shop
light, and wide-spectrum tubes (Chroma 50 and daylight). Red,
high-light-loving plants would probably like a bit more, tho.

> 
> 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 we
> already talking about the enhanced output bulbs when we say that we have two
> watts per gallon?

Visibility (lumens) and plant action spectrum are two utterly different
topics. Don't try to make one into the other. They just barely overlap.
:-)

> 
> 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.  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 of
> these bulbs are way brighter than the standard F40/T12 bulbs. Am I overkilling
> it?  

Almost certainly, IMHO!

> 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?

Can't imagine why you would want to know them, unless the *visibility*
of your plants is too low. Better to get their spectra and select for
strong red and blue output, with just enough green to make the tank
"look" pretty.

Wright

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

Liberalism is totalitarianism with a human face.
                                  Thomas Sowell


Watts/lumens (again?)

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Fri, 22 Jan 1999

On Fri, 22 Jan 1999, Bob Dixon wrote:

>
> Okay, guys, help me out here.  When we talk about two watts per gallon, are we
> talking standard florescents?

Yes.

> By standard I mean those 3180 lumens 40 watt
> tubes that come standard on most light fixtures and are sold in grocery store
> everywhere.  They offer 79 lumens per watt, or thereabouts.  So if I for
> example put two of these over a 40 gallon tank I have two watts per gallon, or
> about 158 lumens per gallon.  But re we talking two 40-watt bulbs without
> decent reflectors?  Or are we talking about light fixture with a reflectivity
> of 50%.  Or are we required to get something like "Coilzak", which has an 89%
> reflectivity minimum guarantee?

Normal reflectors.  White, been used for a while, maybe a little dirty.

> If I use a highly reflective fixture, can I
> say that I have inceased those 158 lumens by 90%, because all the light that
> was going up instead of down is now heading properly into the tank?  Which
> would put me at 300 lumens per gallon.

Nope.  Don't do that.  I'll guess (Erik O. probably knows for sure) that a
practically perfect reflector would only give you a 30% to 50% increase
over an average reflector.  Besides, remember that lumens measure the
brightness of the light as perceived by human eyes.  Lumens aren't
necessarily very meaningful to plants so there's probably not much point
to splitting hairs.

>
> 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 we
> already talking about the enhanced output bulbs when we say that we have two
> watts per gallon?

Nope.  Normal output.

>
> 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.  Now I want some more guidelines.

So we go overboard on chemistry and that should justify our going
overboard on physics, too?  (implied smiley).

> 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?

No.  Maybe the ones that came with the strip light should count as 15
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 of
> these 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?

Four Chroma50's over a 55 gallon tank produces a bright tank.  This batch
will be blinding (IMHO, YMMV, we all see light a little differently, etc,
etc).

I've used Philips Ultralume and Advantage bulbs.  I love them for both
longevity, brightness and color rendition, but I relegated them to the
fixture over my workbench.  I was using four 5000K bulbs (Ultralumes and
Advantage, mixed over my 55) and all of my plants started accumulating
damage on unshaded areas of leaves.  I don't know for sure why that
happened but I found after getting technical assistance from Philips that
the "red" peak in both tubes (these are triphosphor tubes, so their
spectra consist of three separate spikes, one green, one blue-violet and
one orange-red) was actually not a true red; it's orange, and mostly below
the wavelength where plants' red-sensitive pigments operate.  *If* that
was the problem, then your combination of the Ultralumes and Advantage
bulbs with the Tritons probably will avoid the problem.  If I recall
correctly, the red peak in Tritons is a true red - it is at a longer
wavelength than the "red" peak in the Philips tubes.

Philips has a large web site and the technical specs of some of their
bulbs are included there, but I don't have the URL.  They employ a firm in
the US (Philips is a Dutch company) to provide technical support via 800
number and they were quite helpful and friendly.  I don't have the 800
number.  Could I be more helpful? (place a sarcastic smiley here).


Roger Miller
er, I think.


flourescent tubes

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Fri, 22 Jan 1999

On Fri, 22 Jan 1999, Richard Sexton wrote:

> I'm seeing a bunch of statements here about fluorescent tubes that leave
> me shaking my head.
>
> "Plant and aquarium" tubes are gro-lux wide spectrum. They're pink,
> not yellow or orange. Regular gro lux is purple.

Gro-lux and Gro-lux wide spectrum are made by Sylvania, not GE.  That
aside, I've had GE PL/AQ and Sylvania Gro-lux Wide Spectrum tubes on tanks
in the same room.  They do not appear similar, so maybe they're selling
different PL/AQ bulbs there than they are here.

[snip]

> I can't imagine what would make poeple think C50's or PL-AQ's
> look "yellow" or "orange". A warm white might give you this
> impression, but a C50 has a decidely blue tinge to it, and the
> PLAQ's are quite pink.

Warm white lights appear yellow to me, but C50's appear white (not
blue-ish) and PL/AQ's appear yellow, but not as yellow as warm whites.  My
impression of the color of PL/AQ may be "colored" because one of our tanks
that uses the PL/AQ is next to a north window, so the light I'm comparing
it to is very blue.  The other is against an east window, so it doesn't
have that comparison problem, and it still looks a little yellow.

Possibly one reason we have different descriptions of light color is that
we use different standards for reference.  I think I use daylight as my
color reference.  Our daylight here in the high desert is very clear and
probably has a lower color temperature than what many people are
accustomed to. I find the sunlight in Houston (for instance) to be subdued
and bluish by comparison even on what locals there call a clear day.
Certainly the color of sunlight changes to the north, as well.  In Ontario
your sunlight (or whatever passes for sunlight there) might give you very
different expectations than might this brilliant stuff pouring through my
southeast-facing office window.

Some of us may use office light as a standard for comparison.  That's the
only way I can imagine anyone saying (as Steve Pushak did in this volume)
that cool white fluorescents are fine for viewing aquatic plants.  The
blue tint and flat color rendition of a cool white fluorescent drives me
nuts.

>
> I think some of you people are color blind! :-) >

Well, there's that too.  But my color vision was tested recently, and its
just fine, thank you. (insert your favorite smiley).


Roger Miller


Aquatic Plants Digest V3 #798

by "Richard J. Sexton" <richard/aquaria.net>
Date: Sat, 23 Jan 1999

At 03:48 PM 1/23/99 -0500, you wrote:
>Odd. My perception of the GE Super Daylights is that they are a whiter/bluer
>bulb and the Chromas 50s a warmer (somebody mentioned orange?) bulb. So by my
>perception of the color of each bulb, the Super Daylights _should_ have
>produced a more compact growth (they didn't) and the Chroma 50s taller growth
>(the space 'tween nodes has decreased dramatically)? 

That is correct. The "super daylight" (SPX65) has a big spike in the
blue end of the spectrum. The C50 is much closer to a flat spectral
output with all wavelengths (=colors) being represented.

But, all things are relative, and in comparison, the C50 will
look less blue. Now, hold it next to a cool white or warm
white or (especially) a gro lux and it will look *quite* blue.

- --
Richard J. Sexton                                         richard@aquaria.net
Maitland House, Bannockburn, Ontario, Canada, K0K 1Y0       +1 (613) 473 1719


Aquatic Plants Digest V4 #407

by "II, Thomas Barr" <tcbiii/earthlink.net>
Date: Thu, 13 Jul 2000

>Hey Tom,
>
>What is the color temperature of the triton bulbs you use?  Could it be
>that red plants require temperatures >= 5000K?  I see that you have
>6500K and the tritons, what are the temperatures on Neil's tubes.  I am
>curious to see if red plants require higher temperatures to stay red.

This is not true. I have nice red colored plants at 3000K bulbs and 4000K
bulbs.
Higher temps help, but are not a prerequisite. I like a mix of colors
myself. I think the big issue on color temps is the way the colors look to
us. Almost every color(3000-8000K) bulb will grow plant fairly well. How we
see the these colors is another issue.

>
>I use GE plant & aquarium bulbs (full spectrum) - 3050K and Chroma 50s -
>5000K, but I think I may switch the Chroma 50s for Cool Whites - 4150K.

It might look better but the plants are that picky. But the cool whites are
what a- 1$ ea? Sure, why not.
Regards, 
Tom Barr


Dutch aquarium lighting

by busko/stsci.edu (Ivo Busko)
Date: Mon, 11 Dec 2000

I did a quick survey of the nbat Dutch web site to gather some technical
data. I am curious about what techniques they use, and if, and how, they
differ from "our" current lore. I had the impression, when first browsing 
thru the tank descriptions, that there was a high incidence of very low 
color temperature bulbs, at least according to "our" standards. The data 
below confirm this. Note that apart from the "daylight" and Aquarele, there 
is no reference to anything as "blue" as 5,000 Kelvin. Use of incandescent-like 
color temps (around 3,000 K) seems to be the norm instead. There is also
no references to anything different from standard fluorescents, such as MH, 
PC or halogen (or I just couldn't find them...)

The Watts/gal values seem rather low but are consistent with the distribution 
posted by Erik Olson at the krib site, albeit at the lower end of the
envelope. These are in general quite large tanks.

The table includes all planted tanks listed at the 1999 competition pages, 
and also the planted tanks listed at the archive page under "Vivarium in
beeld". I didn't include a couple tanks for which I couldn't make sense of 
the light bulb designations (such as 77). I also didn't include a couple 
tanks with incomplete data.

- -Ivo Busko
 Baltimore, MD



Volume  Watts/gal  Depth     Quantity of bulbs and color type
 (gal)             (cm)

 100      2.87      50       5 X 29, 830, 840
 112      2.57      50       3 X 830, 1 X 840, 1 X 89 (?)
  92      2.50      45       2 X Warm white, 1 X Grolux, 1 X daylight
 110      2.28      50       82, 830
 106      2.18      47       1 X 92 (?), 1 X 930, 1 X 940, 1 X 840
 152      1.90      60       2 X 830, 2 X 840, 1 X Aquarele
 198      1.75      48       6 X 92 (?)
 172      1.67      50       8 X 830
 132      1.62      55       2 X 92 (?), 2 X 940
  90      1.60      50       1 X 89 (?), 1 X 82, 1 x 830, 1 X 840
 283      1.52      55       12 X 830, 840
 124      1.45      60       4 X 830, 1 X 840
 276      1.42      55       89 (?), 930, 940
  86      1.26      50       2 x Warm white, 1 X Aquarele
 146      1.23      50       3 x 830, 1 X 827, 1 X 89 (?)


Color designations:

29  -  2,900 Kelvin, CRI 70 (halophosphor)
82  -  Perhaps a shorthand for 827 ?
827 -  2,750 Kelvin, CRI > 80 
830 -  3,000 Kelvin, CRI > 80
840 -  4,000 Kelvin, CRI > 80
92  -  Perhaps a 2,750 Kelvin, CRI > 90 ? 
930 -  3,000 Kelvin, CRI > 90
940 -  4,000 Kelvin, CRI > 90 

The (?) means no correspondence exists within the Philips European catalog.

I couldn't figure out what the "89" type means, but there is a reference
to a "Aqua Star" brand/type associated with that number.
 


Aquatic Plants Digest V4 #712

by Lennart =?iso-8859-1?Q?Ed=E9n?= <le.e/privat.utfors.se>
Date: Tue, 12 Dec 2000

Hi Ivo,

The "89" type is probably the Philips ´TL`D/89 Aquarelle 10000K that is
widely used in Europe. I use them myself and really like them. They
somewhat compensate for the strong peat tint I have in my tanks. The
10000K rating is a bit confusing since they don´t look that blue to me.
Colour rendition is excellent even though the CRI is only 89.

Lennart 
Norrkoping Sweden


Ivo Busko wrote:
 
> ------------------------------
> 
> Date: Mon, 11 Dec 2000 08:30:08 -0500 (EST)
> From: busko@stsci.edu (Ivo Busko)
> Subject: Dutch aquarium lighting
> 
> I did a quick survey of the nbat Dutch web site to gather some technical
> data. I am curious about what techniques they use, and if, and how, they
> differ from "our" current lore. I had the impression, when first browsing
> thru the tank descriptions, that there was a high incidence of very low
> color temperature bulbs, at least according to "our" standards. The data
> below confirm this. Note that apart from the "daylight" and Aquarele, there
> is no reference to anything as "blue" as 5,000 Kelvin. Use of incandescent-like
> color temps (around 3,000 K) seems to be the norm instead. There is also
> no references to anything different from standard fluorescents, such as MH,
> PC or halogen (or I just couldn't find them...)
> 
> The Watts/gal values seem rather low but are consistent with the distribution
> posted by Erik Olson at the krib site, albeit at the lower end of the
> envelope. These are in general quite large tanks.
> 
> The table includes all planted tanks listed at the 1999 competition pages,
> and also the planted tanks listed at the archive page under "Vivarium in
> beeld". I didn't include a couple tanks for which I couldn't make sense of
> the light bulb designations (such as 77). I also didn't include a couple
> tanks with incomplete data.
> 
> - -Ivo Busko
>  Baltimore, MD
> 
> Volume  Watts/gal  Depth     Quantity of bulbs and color type
>  (gal)             (cm)
> 
>  100      2.87      50       5 X 29, 830, 840
>  112      2.57      50       3 X 830, 1 X 840, 1 X 89 (?)
>   92      2.50      45       2 X Warm white, 1 X Grolux, 1 X daylight
>  110      2.28      50       82, 830
>  106      2.18      47       1 X 92 (?), 1 X 930, 1 X 940, 1 X 840
>  152      1.90      60       2 X 830, 2 X 840, 1 X Aquarele
>  198      1.75      48       6 X 92 (?)
>  172      1.67      50       8 X 830
>  132      1.62      55       2 X 92 (?), 2 X 940
>   90      1.60      50       1 X 89 (?), 1 X 82, 1 x 830, 1 X 840
>  283      1.52      55       12 X 830, 840
>  124      1.45      60       4 X 830, 1 X 840
>  276      1.42      55       89 (?), 930, 940
>   86      1.26      50       2 x Warm white, 1 X Aquarele
>  146      1.23      50       3 x 830, 1 X 827, 1 X 89 (?)
> 
> Color designations:
> 
> 29  -  2,900 Kelvin, CRI 70 (halophosphor)
> 82  -  Perhaps a shorthand for 827 ?
> 827 -  2,750 Kelvin, CRI > 80
> 830 -  3,000 Kelvin, CRI > 80
> 840 -  4,000 Kelvin, CRI > 80
> 92  -  Perhaps a 2,750 Kelvin, CRI > 90 ?
> 930 -  3,000 Kelvin, CRI > 90
> 940 -  4,000 Kelvin, CRI > 90
> 
> The (?) means no correspondence exists within the Philips European catalog.
> 
> I couldn't figure out what the "89" type means, but there is a reference
> to a "Aqua Star" brand/type associated with that number.
> 
>


Dutch aquarium lighting

by busko/stsci.edu (Ivo Busko)
Date: Tue, 12 Dec 2000

Lennart =?iso-8859-1?Q?Ed=E9n?= <le.e@privat.utfors.se> wrote:

> Hi Ivo,
> 
> The "89" type is probably the Philips ´TL`D/89 Aquarelle 10000K that is
> widely used in Europe. I use them myself and really like them. They
> somewhat compensate for the strong peat tint I have in my tanks. The
> 10000K rating is a bit confusing since they don´t look that blue to me.
> Colour rendition is excellent even though the CRI is only 89.
> 
> Lennart 
> Norrkoping Sweden

Indeed, Lennart, I double checked the Aquarelle PDF page at high magnification
and saw the "89" in there. I'm having problems in reading some PDF files 
from the Philips European web catalog. Thanks for the info.

This weakens a little bit my argument: now 7 out of the 15 listed tanks use 
some sort of blue light bulb. Still, it is typically one bulb in a set of 4 
or more, all the others being very yellow. 

Here is the revised table:


Volume  Watts/gal  Depth     Quantity of bulbs and color type
 (gal)             (cm)

 100      2.87      50       5 X 29, 830, 840
 112      2.57      50       3 X 830, 1 X 840, 1 X 89
  92      2.50      45       2 X Warm white, 1 X Grolux, 1 X daylight
 110      2.28      50       82, 830
 106      2.18      47       1 X 92 (?), 1 X 930, 1 X 940, 1 X 840
 152      1.90      60       2 X 830, 2 X 840, 1 X Aquarele
 198      1.75      48       6 X 92 (?)
 172      1.67      50       8 X 830
 132      1.62      55       2 X 92 (?), 2 X 940
  90      1.60      50       1 X 89, 1 X 82, 1 x 830, 1 X 840
 283      1.52      55       12 X 830, 840
 124      1.45      60       4 X 830, 1 X 840
 276      1.42      55       89, 930, 940
  86      1.26      50       2 x Warm white, 1 X Aquarele
 146      1.23      50       3 x 830, 1 X 827, 1 X 89


Color designations:

29  -  2,900 Kelvin, CRI 70 (halophosphor)
82  -  Perhaps a shorthand for 827 ?
827 -  2,750 Kelvin, CRI > 80 
830 -  3,000 Kelvin, CRI > 80
840 -  4,000 Kelvin, CRI > 80
89  -  Aquarelle 10,000K, CRI 70
92  -  Perhaps a 2,750 Kelvin, CRI > 90 ? Couldn't find it in Philips cat.
930 -  3,000 Kelvin, CRI > 90
940 -  4,000 Kelvin, CRI > 90 


- - Ivo Busko
  Baltimore, MD


light attenuation

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Mon, 17 Jul 2000

On Mon, 17 Jul 2000, Wright Huntley wrote:
 
> > Nevertheless, I contend the *difference* in substrate-level available light
> > between an 18"-deep tank and a 24"-deep tank is essentially insignificant.

To which Ivo Busko replied:
 
> Sorry if I misunderstood, but you mean the article is wrong ? According
> to the "pure H2O" curve, which is the one relevant for this purpose, a 
> 16" layer of pure water should absob 15-20 % of the ligth at the 600-700 
> nm band, about 5% at the visible range and nothing at the blue.

Adey and Loveland (1991) gives values for the attenuation of natural PAR
(so, not specific to any particular wavelength) in various natural water
bodies.  I've taken the liberty of converting the values from 1/meter to
percent per foot:

   Oceanic Water
      Sargasso Sea                            0.9%
      Gulf Stream off Bahamas                 2.4
      Pacific Ocean, 100 km off Mexico        3.4

   Coastal and estuarine waters
      Bjornafiord, Norway                     4.6%
      Gulf and California                     5.2
      Tasman Sea, Australian coast            5.5
      Port Hacking estuary, Australia        11.3
      Clyde R. estuary, Australia            21.6

   Inland waters
   North America
      Crater Lake, Oregon                     1.8%
      L. Ontario, Canada                      4.6 - 18
      San Vicente reservoir, California      20
      Lake Minnetonka, Minnesota             21 - 85
      McConaughy reservoir, Nebraska         49
      Yankee Hill, reservoir, Nebraska       76
      Pawnee reservoir, Nebraska             88

   Europe
      Esthwaite Water, England               24 - 49%
      Loch Croispol, Scotland                45
      Loch Uanagan, Scotland                 72
      Sea of Galilea                         15
      Sea of Galilea (Peridinium bloom)     101
      
   Africa
      Lake Simbi, Kenya                      91 - 380%
      Lake Tanganyika                         4.9
      
   Australia
      a) southern tablelands
      Corin Dam                              27%
      Lake Ginninderra                       45
      Burrinjuck Dam                         50
      L. Burley Griffin                      86
      L. George                              460
      b) Northern Territory (Magela Creek bilabongs)
      Mudginberri                            38%
      Leichardt                              51
      Georgetown                            260
      c) Tasmania (lakes)
      Perry                                   6.4%
      Ladies Tarn                            13
      Risdon Brook                           18
      Barrington                             34
      Gordon                                 66

Values of a few percent per foot can be used the way they read.  Higher
numbers are a little problem.  Math-impaired may want to skip down a ways
to where the English starts again.

The coefficients are for exponential attenuation so the coefficient always
overstates the amount of attenuation you would actually get as light
passed through a foot of water.

The equation is:

   I/I0 = exp(-Kd*D/100)

   Kd is the attenuation coefficient given above
   D is the depth in feet
   I0 is the incident light intensity
   I is the light intensity at depth D.

<English here I think> 

I think that means that light attenuation over short distances in pure
water would be insignificant -- less than 1% of the light per foot and
less than 1.3% in 16 inches.  The amount of attenuation in an aquarium
will be pretty variable but like Wright, I expect that our tanks are
usually on the clear side of natural water.  Let's say, something like 5%
per foot on a good day.  In the article I circulated last fall, Davis and
Brinson (1980) cited a value that converts to 6% per foot for clear lakes
like Lake Tahoe.  At 6%, the light penetrating to 24" inches would be
almost as bright (97% as bright) as the light at 18".  There's leeway for
that number to be a little higher and much lower.  Also, reflection and
refraction in a tank would effect the vertical distribution of light.

While this is all very nice I think it neglects the most important factor,
which is the plants themselves.  The plants adsorb red and blue light and
reflect green light, so the light in a heavily planted tank often looks
pretty green.  If you have a deep tank or you let the plants close in at
the surface then the light can get *really* green.  Our eyes are sensitive
to green light, so it still looks only a little darker than the unfiltered
light, but to plants that green light is nearly useless.


Roger Miller

Adey, Walter H. and Karen Loveland, 1991.  Dynamic Aquaria.  Academic
Press, San Diego, Ca. 643 pp.

Davis, Graham J. and Mark M. Brinson, 1980.  Responses of vascular plant
communities to environmental change.  US Fish and Wildlife Service
FWS/OBS-79/33.


Aquatic Plants Digest V4 #609

by busko/stsci.edu (Ivo Busko)
Date: Mon, 16 Oct 2000

"Wayne Jones" <waj@mnsi.net> wrote:

<snip>
> very interested if you were to try some Philips 950 lamps mixed in with the
> 850s and if you thought there was any improvement in plant growth with them.
> I only started using them because of the super high CRI and the fact that
> Frode Ro uses them but was very suprised by an improved plant growth.

Wayne, are you using the US-available Philips TL/950, or the European 
TL'D/950 ? I believe Frode uses the 'D type, and there is a *huge* difference
in performance in between them. .

> Does anyone out there think that the concentrated spikes in an 800 series
> spectrum is in any way less desirable for plant growth than the less spiky
> spectrum found in 950 lamps or even for that matter in cool white lamps.

There is a huge difference in the spectrum between different lamps which 
otherwise bear the same /950 spec. For instance, the TL'D is a true "full 
spectrum" lamp with an even distribution of ligth along the wavelength scale. 
The PLL/950 (Philips compact fluorescent) has a peaky spectrum which is almost 
identical with a /850 tri-phosphor (again the term !) except for the relative
strength of the three main spikes. The TL/950 looks like a tri-phosphor with 
the peaks at the wrong locations, all three in the wavelength range 500-580 nm.

I've been thinking about your idea on the narrow and very brigth spikes being
in some way damaging to plants. I came up with a line of reasoning that
involves both the spectral response of particular pigments in the plant, and
the overall intensity level put out by the lamp relative to "natural"
light. The light put out by the lamp would be damaging to the plant IF the
total light integrated under the pigment's spectral curve, and weighed by the
curve, is much larger than levels found under natural conditions. It  doesn't 
really matter how narrow is the lamp's spike. What is relevant is how narrow 
it is _relative_ to the pigment's spectral response. 

AFAIK most plant pigments have very broad spectral responses with relatively
minor peaks, if any. So the very peaky light put out by the lamp would be
effectively strongly "smeared out" by the pigments' spectral responses. In
other words, the pigment cannot tell apart photons from the exact wavelength
of the spike from photons at any other wavelength under its spectral
response. Or, the pigment cannot "see" the spikes, and would respond in a
similar way to the spiky spectrum as it would to a "full spectrum" put out by 
a say, C50 lamp. What really matters is the _integrated_ ligth.

When smeared in that way, the resulting light level "seen" by the plant at 
any  particular wavelength would be extremely reduced, and probably lower 
than levels existing under natural conditions. I still need to quantify
this line of reasoning though.

Of course, this is all very speculative.

- - Ivo Busko
  Baltimore, MD


Up to Misc. Tech <- Plants <- The Krib
This page was last updated 18 February 2002