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More Comments regarding the Sears-Conlin paper

Contents:

  1. Of fish loads and nitrogen
    by Elizabeth Worobel <eworobe-at-cc.UManitoba.CA> (Thu, 24 Oct 1996)
  2. Too Much Light ?!?!?
    by spush-at-atc-1s.hac.com (Stephen Pushak) (28 Sep 1996)
  3. Who sold PMDD
    by Kevin Conlin <kcconlin-at-cae.ca> (Tue, 05 Nov 1996)
  4. PMDD component stability
    by psears-at-emr1.NRCan.gc.ca (Paul Sears) (Tue, 21 Jan 1997)
  5. PMDD's and Mastergrow
    by psears-at-emr1.NRCan.gc.ca (Paul Sears) (Wed, 29 Jan 1997)
  6. PMDD's
    by krandall-at-world.std.com (Thu, 30 Jan 1997)
  7. PMDD
    by Pat Bowerman <bowerman-at-specent.com> (Mon, 14 Jan 1980)
  8. N-limited/P Limited
    by "Dixon, Steven" <stdixon/bechtel.com> (Sat, 06 Dec 1997)
  9. Nutrient limitation
    by eworobe/cc.UManitoba.CA (Sat, 6 Dec 1997)
  10. Regaurding Evil PO4
    by Tim Mullins <tbm/ix.netcom.com> (Sun, 08 Feb 1998)
  11. Evil PO4---, CO2 cylinders
    by Paul Sears <psears/nrn1.NRCan.gc.ca> (Mon, 9 Feb 1998)
  12. Pull that stump!
    by krandall/world.std.com (Tue, 02 Feb 1999)
  13. KNO3
    by Paul Sears <psears/nrn1.NRCan.gc.ca> (Wed, 24 Feb 1999)
  14. minor gripe
    by Doug Karpa-Wilson <dkarpawi/indiana.edu> (Sat, 8 May 1999)
  15. Trace element supplementation
    by krandall/world.std.com (Sat, 03 Apr 1999)
  16. PMDD calculations, 2nd time
    by Paul Sears <psears/nrn1.NRCan.gc.ca> (Tue, 16 Mar 1999)
  17. gluconate and other K sources
    by "Roger S. Miller" <rgrmill/rt66.com> (Mon, 28 Jun 1999)
  18. PMDD ingredient source
    by Chuck Gadd <cgadd/cfxc.com> (Wed, 29 Nov 2000)

Of fish loads and nitrogen

by Elizabeth Worobel <eworobe-at-cc.UManitoba.CA>
Date: Thu, 24 Oct 1996

You can add nitrogen to your tank. The purpose of this is to reduce the 
phosphate to a level which will no longer support algal growth ... the 
reason that we target phosphate as the limiting nutrient is that it is 
commonly limiting in natural environments so that plants have developed 
strategies for 'hoarding' it. Of course you can try limiting other 
nutrients such as nitrogen but this is difficult since even with no 
nitrates in the water, blue greens can still fix N2. 
When Paul and Kevin first wrote their article on PMDD and their algal 
experiences, they asked me to explain how  higher plants could outcompete 
alga for phosphate. I couldnt answer but have thought about it and done 
some reading since then ... in my opinion the key element is not that the 
plants can compete successfully for available phosphate with the alga 
(they cant since uptake rates are much higher at far lower concentrations 
in algae than in higher plants) but that they can sequester it for far 
longer time periods. In effect, the turnover rate in alga is much faster 
than in higher plants. This means that over time, even though at any
given instant the alga take up a greater proportion of available P, all 
the P in the tank is slowly absorbed by the higher plants. This is 
obviously a slow process which is why patience is required in the 
Sears/Conlin approach. This will be even slower if you have a significant 
amount of P in your tap water ... I would suggest a phosphat absorbing 
filter in your tank along with floating plants to strip the water of P 
even faster (along with the addition of nitrate).

dave.

Too Much Light ?!?!?

by spush-at-atc-1s.hac.com (Stephen Pushak)
Date: 28 Sep 1996
Newsgroup: rec.aquaria.freshwater.plants

timst3-at-vms.cis.pitt.edu wrote:
: >> Alas, my Giant Sag turns red towards the top of the tank and 
: >> browns. My pigmy swords are an enemic light green (Iron is 0.1 ish,
: >> magnesium ought to be ok). My Hygrophia is somewhat stunted with 
: >> vast root systems on the upper stems, rotting lower stems, and
: >> redish - army greenish leaves. My Rotilia is a nice red however.

It may be that you are liking in Nitrogen (ammonium or nitrate/nitrite)
but I will defer that judgement to those more knowledgeable about
nutrient deficiencies. PMDD will fix a lack of Nitrogen nutrients.
You're certainly not lacking Fe or CO2 from your information however
the Tetra test kit is extremely inaccurate in my experience. I use
the Lamotte kit which has an excellent reputation and accurate to +/-
1 ppm.

: Despite my lurking, PMDD is still a mystery. Is this the home
: brew daily additive? I do add flourish daily (in proportioned
: doeses given their weekly recommendation). Might you be able to
: fill me in on PMDD? Also, will nutrient shortages explain
: excessive redding on the upper Sag leaves and my Hygrophia
: problem (sorry about the spelling)?

Red leaf coloring is not a bad sign but generally means sufficient
light and iron. Even H poly will get an olive color with good light
and Fe.

PMDD is a daily additive which contains macro-nutrients,
Potassium, Nitrogen, Magnesium and Sulfer. I had a good improvement
of growth and coloration after switching from Flourish to PMDD.
I believe what PMDD doesn't have which may be needed for some or
many people is Calcium. Just because we have hard water doesn't
mean there is enough Calcium; the hardness can be Mg. See Paul K's
recent posting on the APD about Calcium deficiency symptoms.

Here is the PMDD recipe again for those hunting for it:


~From: Kevin Conlin <kcconlin-at-cae.ca>
~Date: Wed, 13 Mar 1996 13:33:27 -0500
~Subject: PMDD recipe

Back by popular demand!

  1 Tbsp Chelated Trace Element Mix (7% Iron + B, Mn, Mo, Zn, Cu)
  2 Tsp K2SO4 (potassium sulfate)
  1 Tsp KNO3 (potassium nitrate)
  2.5 Tbsp MgSO4.7H2O (fully hydrated magnesium sulfate, aka epsom salts)
  300mL distilled H2O
  0.5mL 9M HCl (optional)

Dissolve the trace element mix in 150mL distilled water, then add the
remaining ingredients.  Add additional water to make 300mL solution.
The HCl helps prevent the growth of fungus and may be omitted if the
mix is kept in the refrigerator (sorbic acid may work better; anyone
care to try?).  Add enough mix to the tank every day
to keep the Fe level at about 0.1ppm (the exact amount will have to be
determined by experimentation, but 3mL per 100L tank water is about
right for a tank with rapidly growing plants).  Measure nitrate levels
regularly, and adjust the amount of KNO3 in the mix to maintain about
5-10ppm (this step is fairly important, and for some it may be more
practical to dose the macronutrients separately).  If test kits
are not available, satisfactory results can be obtained by adding 1mL
mix to 10L replacement water during water changes.  Most of the
ingredients can be purchased at hydroponics shops or garden supply
stores.  Epsom salts are available inexpensively at pharmacies.

If your local trace element mix has 4% Fe plus Mg (in addition to B, Mn,
etc), you'll need to modify the recipe slightly by omitting the epsom
salts and increasing the amount of trace element mix slightly.

With a little legwork, you should be able to get a lifetime supply
of the chemicals for about $25, much less if you get a few friends together
and buy the stuff in 50lb bags.   For a few hundred bucks you could
treat one of the smaller Great Lakes.
- --
Kevin Conlin   kcconlin-at-cae.ca   "We're Canadians.  We HAVE to be polite"
Finger as332-at-freenet.carleton.ca for PGP public key.


To locate North American retailers of the Canadian mix you might
try calling the wholesaler listed below. It is sold at some shops
in the U.S. The product is Chelated Micronutrient Mix made by

Plant Products Limited
314 Orenda Avenue
Brampton, Ontario  L6T1G1
Canada
Tel. 1-905-793-7000

I should get $5 every time I post this address and number.

- --
Dave Whittaker                       ac554-at-FreeNet.Carleton.CA
Gloucester, Ontario                  dwhitt-at-magmacom.com
Canada

==========================================================

From kcconlin-at-cae.ca Fri Jun 28 17:44:05 1996
On Friday, 28 June 1996, Stephen.Pushak-at-hcsd.hac.com wrote:

> Let me know if you find out a price. I think it was pretty cheap.
> David Whittaker or Kevin Conlin might know the price offhand. 
> I recall a very cheap price mentioned on the APD but I can't find 
> the reference now. I'll cc them to see if we get an answer this
> afternoon. The price from one hydroponics store here in Vancouver
> is $.10 / GRAM!! That's about $100 / Kg.

I paid $20/Kg and felt ripped off.  Since there are several of you,
you could try to order a 25Kg bag and peddle the excess.  Lots of people
have written to me inquiring about a mail-order source for the stuff.
--
Kevin Conlin   kcconlin-at-cae.ca   "We're Canadians.  We HAVE to be polite"
Finger as332-at-freenet.carleton.ca for PGP public key.

==========================================================

From PacNeil-at-aol.com Sat Jun 29 21:46:47 1996

In a message dated 96-06-28 18:50:25 EDT, you write:

<< How much did you pay for the micronutrient mix? Where did you get it?
 We can get it locally but at $.10/gm its pretty pricey!
 Try looking for hydroponics outlets; they should have the
 rest of the ingredients and in smaller lots for the right price. >>

I bought the micronutrient mix from an agricutural supply house. The 5# bag
cost $23.00. The other ingredients were available there in 50# bags. Not
expensive, but a little too large a quantity for my purposes, unless I used
the remainder in my yard. The only hydroponics store listed in the yellow
pages, didn't have a clue what I was talking about. The avocado and citrus
growers around here use the ingredients on their trees. I found all the
ingredients. The last one,  Pottasium Nitrate, is sold a stump remover.
Fortunately I found an employee, at a Nursery, that knew this tidbit. I've
been using the PMMD for about three days now and some of the plants seem to
already be responding. 
C-Ya
Neil Schneider 

==========================================================

From ac554-at-freenet.carleton.ca Sun Jun 30 00:41:19 1996

2 kilograms for Can$38.00

--
Dave Whittaker                       ac554-at-FreeNet.Carleton.CA
Gloucester, Ontario                  dwhitt-at-magmacom.com
Canada

--
 Steve Pushak - spush-at-hcsd.hac.com - Vancouver, BC, Canada

 -------------------------------------------------------
 |    Don't fear what you face; face what you fear!    |
 -------------------------------------------------------



Who sold PMDD

by Kevin Conlin <kcconlin-at-cae.ca>
Date: Tue, 05 Nov 1996
Newsgroup: rec.aquaria.freshwater.plants

Tim Mullins wrote:

> A little while ago someone posted a price
> for suppling a pre-mixed PMDD for those
> of us having trouble locating ingrediets.
> Could you re-post or send me e-mail.

PacNeil-at-aol.com.  I can supply people in the Montreal area who
are willing to come pick it up.

Incidentally, I've found that the following recipe works better now
that my UV is off: 1 tbsp trace element mix, 1 tbsp epsom salts,
1 tbsp KNO3, and 2 tbsp K2SO4 in 500ml H2O.  If your nitrates are
currently on the high side, hold off on the KNO3 until they drop
to unmeasurable levels.
-- 
Kevin Conlin  Montreal, Canada  "We're Canadians.  We HAVE to be polite"
Finger as332-at-freenet.carleton.ca for PGP public key.


PMDD component stability

by psears-at-emr1.NRCan.gc.ca (Paul Sears)
Date: Tue, 21 Jan 1997

> From: James Wong <u2120863-at-acsusun.acsu.unsw.edu.au>
> Subject: Precipitation of chemicals other than Fe
> 
> I have a dumb question for the chemists on the list.

        Not dumb at all...
> 
> My question is do the other chemicals in the PMDD mix precipitate out of 
> solution or degrade prior to their addition into a fishtank? If so which 
> ones and under what conditions?

        Mg++, K+, NO3-, SO4--   Not at all, and not in the tank either.
        Mn, Cu, Zn, Fe as chelates should be chemically stable, but
liable to attack if kept in light, and probably liable to bacterial
/fungal? attack as well.
        MoO4--, B(OH)3 should be stable, though the MoO4-- may (slowly)
attack the chelating agent on the first four metals.
> 
> I ask this becasuse I'm thinking of making my next batch of PMDD with the
> Fe solution seperate from the rest of the ingredients

        It would certainly be O.K. to make up and keep a solution of
the MgSO4(12? H2O), KNO3 and K2SO4, probably for years.
        
        I'll take this opportunity to mention the fact that the idea
of the original posting in which "PMDD" occurred was to explain a
_method_ for algae control, not just a recipe for a fertilizer.

        The idea is that most planted aquaria are short of potassium
and trace elements, so add them.  The plants can then use any nitrogen
available, so the nitrate concentration will start to fall (if there was
any to start with).  Add enough nitrate to keep a few ppm in the water
Adding magnesium is usually a good idea too.  If the algae don't give
up over a few weeks, add more potassium.  This is the one thing we can't
easily measure, but I find that algae outbreaks are usually accompanied
by holes in older leaves, and both stop when more potassium is added.
I find that hygro shows the K shortage first.

- -- 
Paul Sears        Ottawa, Canada

Finger ap626-at-freenet.carleton.ca for PGP public key.

PMDD's and Mastergrow

by psears-at-emr1.NRCan.gc.ca (Paul Sears)
Date: Wed, 29 Jan 1997

> From: krandall-at-world.std.com
> Subject: PMDD's and Mastergrow
> 
> I'm not disagreeing with your
> approach, or your advice.  But I also know how many beginner aquatic
> gardeners _start_ with high nitrate levels.

        If they have no nitrate in their tap water, they are short
of K, trace elements or both.  I wish people would _read_ what we
wrote rather than using another fertilizer recipe blindly.  Only
add the nitrate if you can drive the tank nitrate to unmeasurable
levels.  This is not difficult.

> BUT at the same time, I
> think it's usually safer for beginners to go the laterite/ liquid trace
> element route, since I ASSUME that most of them will over stock and over
> feed, under plant and under light.<g>

        If they do all those things, I think they are sunk anyway!  Start 
with K and trace elements (I'm not sure what, if anything, laterite does),
and use nitrate if required.  It is not complicated, but one _must_ use
enough potassium, and I think most don't.

> Sometimes we forget, here in the list, that by the time someone makes it to
> this list, whether they seem like "newbies" to the really experienced folks
> or not, that they are already light years beyond the "average" hobbyist.

        I think the problem is that the subject has been something close
to a black art for a very long time.  "Fertilizers" and other additives
with unlisted ingredients, lots of conflicting stories about what causes
what, and an appalling ignorance of basic chemistry have left almost
everyone in the dark, hoping to find a set of conditions that lets
them keep a half-way decent looking aquarium.

        It does not have to be like that! 

- -- 
Paul Sears        Ottawa, Canada

PMDD's

by krandall-at-world.std.com
Date: Thu, 30 Jan 1997

Paul Sears wrote:

>       I am now of the opinion that if there is little nitrate in the 
>water supply and no major source of potassium in the substrate, most tanks
are
>short of potassium.  This then means that the plants cannot use the 
>nitrogen, and nitrate builds up.  I think that a lot more tanks would be
>"nitrogen limited" if potassium were supplied adequately.

Another point in favor of Mastregrow for those who don't want to fine tune
their own formula.
Mastergrow contains relatively large amounts of K and Mg as well as much
smaller amounts of trace elements.

Paul also wrote:

>> I'm not disagreeing with your
>> approach, or your advice.  But I also know how many beginner aquatic
>> gardeners _start_ with high nitrate levels.
>
>       If they have no nitrate in their tap water, they are short
>of K, trace elements or both. 

Not if they are even shorter on light, which is very often the case.

>  I wish people would _read_ what we
>wrote rather than using another fertilizer recipe blindly.  Only
>add the nitrate if you can drive the tank nitrate to unmeasurable
>levels.  This is not difficult.

I have, and I understand your point.  But I've also been working with
enough planted tank beginners for long enough that I have to be realistic.
No matter how carefully you word something, whether in writing or a
lecture, SOME of the people are going to latch on to some (possibly totally
insignificant piece of information) and miss the whole point of what you
are trying to get across.
>
>> BUT at the same time, I
>> think it's usually safer for beginners to go the laterite/ liquid trace
>> element route, since I ASSUME that most of them will over stock and over
>> feed, under plant and under light.<g>
>
>       If they do all those things, I think they are sunk anyway!  Start 
>with K and trace elements (I'm not sure what, if anything, laterite does),
>and use nitrate if required.  It is not complicated, but one _must_ use
>enough potassium, and I think most don't.

Here, I'm sorry, but you are absolutely wrong.  While your method may be
more scientific, and possibly easier if you understand what you are doing,
I _guarantee you_ that there are many people who are fairly clueless, but
are maintaining beautiful, healthy planted tanks that are relatively algae
free using laterite and a good trace element supplement, depending on fish
food/waste as the major source of NPK.

>> Sometimes we forget, here in the list, that by the time someone makes it to
>> this list, whether they seem like "newbies" to the really experienced folks
>> or not, that they are already light years beyond the "average" hobbyist.
>
>       I think the problem is that the subject has been something close
>to a black art for a very long time.  "Fertilizers" and other additives
>with unlisted ingredients, lots of conflicting stories about what causes
>what, and an appalling ignorance of basic chemistry have left almost
>everyone in the dark, hoping to find a set of conditions that lets
>them keep a half-way decent looking aquarium.

I have to agree with you completely there.

>       It does not have to be like that! 

Ditto.


Karen Randall
Aquatic Gardeners Association


PMDD

by Pat Bowerman <bowerman-at-specent.com>
Date: Mon, 14 Jan 1980

I seem to have created some confusion when I attempted to post the
"new" formula for PMDD. Please note that no matter which formula you are
using, the goals are still the same, that is, you are trying to achieve
certain levels of both iron and nitrates. 0.1 ppm iron and about 3-5ppm
nitrate. 
    In an attempt to clear up the confusion, I have forwarded an
off-list e-mail conversation between myself and Kevin Conlin.  

Kevin Conlin wrote:
> 
> On Sunday, 24 December 1995, Pat Bowerman wrote:
> 
> >     I finally bought a LaMotte nitrate test kit, and now I have a
> > question about it. It says that readings are given as ppm nitrate
> > nitrogen. It also says to convert to ppm nitrate, multiply by 4.4. Now
> > my question, when you are talking about nitrate levels, are you talking
> > ppm nitrate nitrogen or ppm nitrate?
> 
Kevin Conlin:
> I'm measuring ppm nitrate.

Pat:
> >     Could you perhaps enlighten me on the differences?
Kevin:
> PPM nitrate measures the amount of nitrate ion NO3-.  PPM nitrogen
> just measures the amount of N.  The factor of 4.4 is the ratio of
> the molecular weight of nitrate to the molecular weight of N.
Pat: 
> > I also understand
> > that you have tweaked the formula for PMDD somewhat. I remember reading
> > that you reduced the MgSO4 among other things. Is there a place where
> > the new formula is posted, and would you care to elaborate on your
> > thinking as to why these changes were necessary?
Kevin:
> The new formula is 1tbsp trace element mix, 1tbsp epsom salts, 2tbsp
> KNO3, and 2tbsp K2SO4.  My original formula was developed while I was
> using a UV sterilizer.  When I turned off the sterilizer, I needed
> much less PMDD to maintain my iron levels, and the plants ran short
> of macronutrients, primarily K.  I cut back on the epsom salts because
> 1tbsp seemed to work just fine; no sense adding more than necessary.
Pat:
> >     Thanks for your help, and most of all.........MERRY CHRISTMAS!
Kevin: 
> Merry (belated) Christmas, and a Happy New year!
> --
> Kevin Conlin  Montreal, Canada  "We're Canadians.  We HAVE to be polite"
> Finger as332-at-freenet.carleton.ca for PGP public key.



N-limited/P Limited

by "Dixon, Steven" <stdixon/bechtel.com>
Date: Sat, 06 Dec 1997

Karen Randall, Jeff Kropp and I have had an off-line conversation that
might be of interest to the group.

Steve wrote:
Jeff Kropp and I have been chatting (almost daily recently) thinking
about trying to reconcile your reports on your tanks with the whole
N-limited PMDD story.  Paul Sears' note yesterday got us going again.
What Paul described was a P-limited situation where he added P (to the
water column, I presume) and watched the nitrate levels drop noticeably.
 The thought was that the extra P allowed additional uptake of nitrates
that otherwise would have been left in the water column.  This confirmed
the P-limited situation in the tank Paul described, as I understand it.

Karen wrote:
That certainly sounds accurate, and is what I would expect to see.  You
just have to hope that the higher plants capture those nutrients before
the algae kicks in.

Steve wrote:
You report fairly regularly that your tanks almost always have zero or
near zero nitrate levels and 'just detectable' P levels in the water
column -- without significant algae problems of any kind.  Your
situation is complicated in my view by two additional facts:  You do add
nitrogen to your tank, but only in the substrate (Jobe's spikes, if I
recall, punched deep into the substrate).  You also keep certain plants
in pots which contain soil (with at least some additional nutrients,
perhaps including N).

Jeff and I keep wondering whether your tanks are N-limited?  They may
not be N-limited if you are successful at introducing N in the substrate
and keeping it out of the water column.  We do know that your tanks are
not P-limited because you report at least some P in the water column.

Karen wrote:
I also think that plants are generally excellent scavengers.  I think it
is entirely possible for them to use smaller amounts of nitrogen from
the water than we can test for.  Let's face it.  You won't find _any_
nitrate in the water unless some ammonium is getting past the plants and
being processed by nitrifying bacteria.  (BTW, I think this is also true
for iron.  I have never tested to make sure I have specific levels of
iron in the water,  I think that specific iron levels are irrelevant.
Plants can and do store more iron than they need for growth.  Therefore,
if there is _any_ measurable iron in the water, you are meeting the iron
needs of your plants.

Steve wrote:
We were thinking of a simple experiment (essentially the opposite of
what Paul was describing yesterday) which might resolve the question.
If you added nitrates to your water column and observed a noticeable
drop in the P levels, we think this would suggest that your tanks really
are N-limited.  (The addition of the limited nutrient N resulted in
additional uptake of P.)  If there were no drop in P levels, this might
suggest that your tanks aren't N-limited after all; that you are putting
enough N in the substrate to avoid this condition.  

I have the feeling this could be significant information.  If the P
levels dropped upon the addition of NO3 to the water column, I would
want to theorize that one can have a very successful planted tank which
is N-limited (though not N-starved) so long as the P level remains in
the 'just detectable' range.  

If it turned out that your tanks were not N-limited, then this puts
another notch in gun stock of the N-limited folks, it seems.
[Inartfully put to say the least.  I  didn't really mean to suggest a
competition of that sort. <g>]  We might conclude that so long as we
avoid the N-limited situation (however we accomplish that) we can
tolerate a bit of P in our tanks; that we don't need to reach a
P-limited situation so long as we avoid an N-limited situation.

What do you think?  Any interest?

Karen wrote:
I am quite sure that my tank WATER _is_ N.  limited, at least in my more
strongly lit tanks.  If I don't add the Jobes sticks, my plants show
clear signs of N deficiency.  In fact, I'd love it if we could talk some
fertilizer manufacturer into formulating a solid N-K fertilizer for use
in planted tanks.

Jeff wrote in a later note:
Stump remover [KNO3] is a solid, but needs dilution some how... powdered
clay, Knox blocks?

Karen wrote:
I don't want to make my own... I want someone else to do it for me!<g>
You
could always roll it in clay, but you'd have to experiment on the
quantities needed.

Jeff wrote:
Tetra Hilena Crypto Total N 1% from Ethylendiaminetetraacetic acid
(proprietary name?) 0.5% water soluble N from Ethylendiaminetetraacetic
acid iron salt soluble K20 25% from Potassium Sulfate

Karen wrote:
I haven't seen that Tetra products do much of anything for my plants.  I
suspect 1.5% N is just too low to have much effect.  My Jobes sticks
work much better.

Karen continued responding to my note:
In a few low light tanks, where I have not had much in the way of fast
growing plants, but also haven't had algae problems because of the lower
light levels, I have sometimes in the past measured N levels as high as
20mg/L.  In these tanks the plants show no signs of nitrogen deficiency,
and I would not, of course, supplement either N or P.  Another telling
point is that the Java Ferns, which, of course, must meet their needs
directly through the water column grow consistently larger in these
tanks than they do in the more strongly lit  nitrate limited tanks.

I just feel that it is "safer" for the display type tank to supplement
macronutrients via the substrate, if at all possible, rather than the
water column, where it can be accessed by algae.  The plants tell me
fast enough if they need food, and it's cheaper than all those test
kits.<g>

I think I'll pass on the experiment of adding N to my water, because my
tanks are happy, healthy and algae free as it stands now, and I feel
that I can adequately meet their needs via substrate supplementation.  I
really don't want to turn my tanks into pea soup just before the
holidays.<g>  As I think I've mentioned before, all of my tanks are in
the living area of our house, not tucked away in a "fishroom" where I
could experiment without the tanks being seen.

I _do_ know that this is not an isolated occurrence effected in some way
by local tap water concentrations, because I have been instrumental in
the setup of many other tanks in areas with very different tap water,
and they all behave similarly.  I can't give you absolute readings from
these other tanks because, again, unless there's a problem, I don't
spend much time using test kits.  I only know where mine stand because
I've tested out of curiosity from time to time.

I think the bottom line is that you can probably limit algae by limiting
one of several nutrients in the water column.  Diana Walstad does it by
limiting iron in the water column.  She's got way high N and P levels by
our standards, but I've seen her tanks in person, (in fact, I used a
photo of one of them in my Dec. AFM column) and the plants are healthy,
and there is no visible algae, even with few or no algae eaters in the
tanks.  In fact, the tank that I used the picture of, has one 1" long M.
boesemani fry in it.  Diana "feeds" the tank fish food, even though
there are essentially no fish in the tank.  She says she has done the
same in the past with tanks that were totally fish-less.  

This certainly isn't an approach I'd use, or advocate, particularly in a
strongly lit tank.  But it clearly works for her.  (BTW, her tanks are
soil based, which gives the plants their prime nutritional source)

Another random thought that needs to be somehow factored in to this
discussion is the "Dupla" style tanks in Europe.  These tanks routinely
run well, and have no real algae problems even when each water change
floods the tank with a new supply on nitrate from the tap water.  I have
been told that these tanks often run relatively algae free with nitrate
in the range of 20 mg/L.  I can only assume that either the tanks are
phosphate limited, or that even though they are open topped and lit with
MH or MV lighting, that the lights are high enough that the effective
light level within the tank is actually quite low.

I am convinced that Kevin and Paul's PMDD system works, not only for
them, but that it is also reproducible by others.  (If you've been
reading my Aquarium Frontiers column, you'll have noticed that I've
directed people to it at least twice)  I also know that my method works
and is reproducible under a variety of conditions.  For the people I
work with, my method is probably preferable, because they are mostly
novices who would be intimidated by the idea of lots of testing, let
alone the need to brew your own supplements.  I encourage them to use
their eyes and common sense instead.<g>  

I also would not be happy with the progression of various algae types
that I seem to hear is quite common during the calibration stage of
working with PMDD's, whether in a new or established tank.  I don't
_want_ to have to wait out various algae problems... I want an
attractive tank that is free of visible algae from day one if I can at
all manage it.  I think this is very important for people who are just
getting started with planted tanks as well.  I think that many would get
discouraged and quit if they had to wait through multiple blooms of
various algae types. Not to sound too smug, but my method produces algae
free tanks with healthy plants even in the hands of most novices.

Karen


Nutrient limitation

by eworobe/cc.UManitoba.CA
Date: Sat, 6 Dec 1997

A few points;

Any nutrient can be used as a limiting nutrient, however;
It is difficult to have an algal free N limited tank because blue-green 
algae can fix N2.
It is relatively difficult to have an algal free Fe limited tank because it 
is a micronutrient and therefore small amounts can produce large algal 
blooms.
IMHO, the easiest to use as a limiting nutrient is phosphorus. It is used 
in relatively large amounts by plants and can easily be omitted from 
water-based plant fertilizers. Having said that, its important to 
understand that macrophytes can in no way outcompete algae for P. Algal 
uptake kinetics are such that they can drive the P levels far lower than 
macrophytes can... after discussing this with Sears and Conlin and 
thinking about it for a few months I came to the conclusion that the 
algae become P limited because the TURNOVER rate of P in algae is much 
higher than in macrophytes. As the P becomes available (through algal 
senescence) the macrophytes 
sequester just a small amount but keep it much longer so that over time 
the algae eventually lose out. This is at present not supported by any 
research that I know of.
Diana's systems of course are sediment based and allow the removal of 
BOTH N and P from the water column... a strong argument for fertile 
substrates in my mind... of course you cant have non-rooted plants under 
these conditions.

dave.

Regaurding Evil PO4

by Tim Mullins <tbm/ix.netcom.com>
Date: Sun, 08 Feb 1998

>Date: Fri, 06 Feb 1998 10:06
>From: "Dixon, Steven" <stdixon-at-bechtel.com>
>Subject: Evil PO4
>
>>Tim wrote:  Tim Mullins - Pittsburgh
>>
>>(who has found the heretofore evil PO4
>>quite useful in my PMDD regimine as of
>>late)
>
>Tim, what form of the evil PO4 are you
>dosing your aquarium with?

Ah, the evil PO4. Well, ok, not completely
evil, but if dosed improperly. . . algae!!!

I use KH2PO4 (MonoPotassium Phosphate)
in a 1% solution(about 1/2 teaspoon in
1/3 litre water). A one-time 1ml dose
of this strength in my 90 gallon tank
(85 G water column) boosts PO4 by about
.02mg/ltr (Rumor has it a _total_ PO4
concentration in the aquarium of .02mg/ltr
is a reasonable bogie).

Why do this????? Maybe you shouldn't.
Turns out I was quite phosphate limited
in my Dupla style 90 gallon. My particuars:

1) I've played with PMDD for awhile now.
I've altered the standard formula a bit
to increase macro nutrients to trace
ratios. My current non-standard mix is:
  5 teaspoons KNO3
  3 teaspoons K2SO4
  1 teaspoon  MgSO4 + 7H2O
  1 teaspoon  Trace (14partsCSM + 1partH3BO3)
  1/3 litre of water
Of course, everybody best tweek their own.
I dose 4ml daily of this mix in my 90.

2) I bubble dose CO2 to average 10mg/ltr.
Lighting is 200 watts of VHO aquasun. I use
substrate heating with laterite in lower
1/3. Water changes are 1/6, twice a week.
Light fish load (3 mollies, 5 SAEs, 12 Ottos),
heavily planted. Some of my nutrient levels:
  NO3 = 5 mg/ltr
  K   = 8 mg/ltr (Yes, LaMotte makes a test!)
  PO4 << .05mg/ltr (PO4 dosing aside)
  Fe  < .05
  Ca  = 60
Pretty soft water with pH averaging 6.6
after CO2 injection.

3) Ok, so what? You see, I always measured PO4
to be way below .05mg/ltr (LaMotte limit).
Good, right? But:
- - Old growth on my Pygmy Swords browned 
  away. Lots O' dead leaves.
- - India Star (Zosterifolia) would spirt
  and stop. Stems would rot.
- - Val would spirt when first planted, then
  slowly melt (substrate depletion of P I
  suspect but can't say conclusivly)
- - Newborn Crypts were staying dwarfed.
- - Java Fern had minute black spots
  (other than those from spores)
- - Aponogetons would use up their stores
  and languish

Over time I had tried juggling PMDD ingredients
to find what was in short supply (Mg?, Fe?, etc.)
I also tried chemical substrate additatives like
Jobes 16-2-6, Crypto Dunger, PMDD to the roots
via hypo. Only the Jobes did much (note the NPK).

I might add I have had luck experimenting
with Steve Pushak's "organic substrates"
in other tanks, but my 90 is ala Dupla style.

4) So, last resort, PO4 addition. Why a last
resort? Like I said, the evil PO4! I knew my
90 was phosphate limited. This was my goal via
Conlin and Sears. BUT. . .,apparently it was
way too phosphate limited! Since adding PO4
things have really greened up and old growth
now STAYS GREEN.

5) Algae? Sure. Too much PO4 and I get spot
and the green velvety algae on the glass
(later easy to remove). Other types haven't
been a problem, praise be the SAE. Still,
very easy does it with PO4. I believe Conlin
and Sears really got it right!

6) I'm still playing with PO4 dosing.
Sometimes I'll add a ml to the water column.
Sometime I'll inject it via hypo into the
substrate. I sure don't put in in every day.
The plants are my guide. One observation:
if I dose KH2PO4 to the column at night,
I swear it leads to less algae and better
higher plant growth than if I dose it in
the morning with my PMDD. Can't yet say
anything conclusive though.

7) Of course I could bag all the PO4 stuff
and just add more fish (and food).   :-)

Tim Mullins - Pittsburgh

P.S. Anyone what to buy a slightly
     depleted 2 litre size of PhosGaurd
     for $6 plus shipping?   ;-)

Evil PO4---, CO2 cylinders

by Paul Sears <psears/nrn1.NRCan.gc.ca>
Date: Mon, 9 Feb 1998

> From: Tim Mullins <tbm-at-ix.netcom.com>
> Subject: Regaurding Evil PO4
> 
> >Date: Fri, 06 Feb 1998 10:06
> >From: "Dixon, Steven" <stdixon-at-bechtel.com>
> >Subject: Evil PO4
> >
> >>Tim wrote:  Tim Mullins - Pittsburgh
> >>
> >>(who has found the heretofore evil PO4
> >>quite useful in my PMDD regimine as of
> >>late)

	Same here.
> >
> >Tim, what form of the evil PO4 are you
> >dosing your aquarium with?
> 
> I use KH2PO4 (MonoPotassium Phosphate)

	I use any of K2HPO4, KH2PO4 or H3PO4. The doses are so small
that pH changes are negligible, whatever I use.

> Why do this????? Maybe you shouldn't.
> Turns out I was quite phosphate limited
> in my Dupla style 90 gallon. My particuars:

	The 160 L tank described in the original article that Kevin and
I wrote also became phosphate limited.
> 
> - - Old growth on my Pygmy Swords browned 
>   away. Lots O' dead leaves.

	ditto.  Also, hygro and hygro difformis died off.  Old leaves
fell off, and the plants gave up growing.

> - - Val would spirt when first planted, then
>   slowly melt (substrate depletion of P I
>   suspect but can't say conclusivly)

	My experience was a bit different.  Giant Val just about took over.

> 4) So, last resort, PO4 addition. Why a last
> resort? Like I said, the evil PO4! I knew my
> 90 was phosphate limited. This was my goal via
> Conlin and Sears. BUT. . .,apparently it was
> way too phosphate limited! Since adding PO4
> things have really greened up and old growth
> now STAYS GREEN.

	ditto.  Mind you, when I first started adding nitrate, I was really
paranoid about that, too.  I was less worried about the phosphate, by the
time it went in - logic really does work!!!!

> 5) Algae? Sure. Too much PO4 and I get spot
> and the green velvety algae on the glass
> (later easy to remove). Other types haven't
> been a problem, praise be the SAE.

	I haven't seen anything but the spot algae, so far.  My (ex-Kevin)
Farlowella gets so little algae that he trashes one of the crypt varieties.

> Still,
> very easy does it with PO4.

	Indeed.  :)

> I sure don't put in in every day.

	Same here.

> The plants are my guide. 

	The best guide of all.  I'm still a little puzzled by the repeated
statements that the method Kevin and I put forward is a "high-tech" method
with lots of measurements.  I do _some_, but the appearance of the plants
and algae (what algae?) is the main guide.

> if I dose KH2PO4 to the column at night,
> I swear it leads to less algae and better
> higher plant growth than if I dose it in
> the morning with my PMDD. Can't yet say
> anything conclusive though.

	I'll have a try this way, too.
> 
> 7) Of course I could bag all the PO4 stuff
> and just add more fish (and food).   :-)

	I never thought of that........  :)

> Tim Mullins - Pittsburgh

	Thanks for the posting.

	As for CO2, why are people fooling around with yeast setups?  I
admit that I paid about $175 CDN for my cylinder setup (no controller),
but it has run for something like 3 years so far on its first filling,
and I haven't adjusted anything in months!  I still have a fairly strong
suspicion that its main function is to keep the pH down in the 160 L tank,
and that it doesn't have all that much effect on the plants, but the tetras
breed in there, so I'm happy with the setup.

	On another topic, I'm trying to set up a Java Moss free tank!
I've come to the conclusion that it functions the way algae do in most
places.      ;)

- -- 
Paul Sears        Ottawa, Canada

Pull that stump!

by krandall/world.std.com
Date: Tue, 02 Feb 1999

Dave G wrote:

>At 03:48 AM 2/2/99 -0500, Bob/Georgia asked:
>>Subject: where to buy KNO3??
>
>Go to your local garden supply or landscaping supply center and ask for
>stump remover.  Be sure to verify that it is Potassium nitrate and not some
>other substance.

I'll second that.  I picked up a package of "stump remover" quickly at Home
Depot recently.  It was a brand I didn't recognize, but I was in a hurry,
and not wearing my glasses, so I couldn't read the fine print.  When I got
home and looked at the label more carefully, I couldn't find any reference
to potassium nitrate on the label.  I was a little concerned, so I put a
small amount in a glass of water and tested it for nitrate.  I don't know
what _is_ in it, but there wasn't any nitrate!  That can is now residing in
the garage waiting for the next time we actually need something to burn a
stump with.<g>  

I believe that Green Thumb and Cookes are 2 brands that _are_ potassium
nitrate.  Unfortunately, I can't remember the name of the one that wasn't,
and it's pouring, so I'm not going out to the garage to check!<g>


Karen Randall
Aquatic Gardeners Association


KNO3

by Paul Sears <psears/nrn1.NRCan.gc.ca>
Date: Wed, 24 Feb 1999

> From: tconnors@webtv.net (Thomas Connors)
> Subject: KNO3
> 
> I couldn't find stump remover at our local garden shop but I did find a
> bag that stated 'potasium nitrate KNO3, guaranteed analysis- total
> nitrogen....13.75% (13.75% nitrogen in nitrate form). Soluble potash
> (K2O) ....44.50%. Would the potash be safe for the planted aquarium? The
> material is small white pellets .

The stuff is KNO3, all right.  The "potash" content is just an odd way
of stating potassium content that results from a convention used for
fertilizers.  For pure KNO3, the N content is 13.9%, the potassium
content is 38.6%, and the "K2O" (which isn't actually there) content
is 46.5%

- -- 
Paul Sears        Ottawa, Canada


minor gripe

by Doug Karpa-Wilson <dkarpawi/indiana.edu>
Date: Sat, 8 May 1999
To: erik/thekrib.com

Hey, Erik,

I love your site, and I"m always poking around.  So far I've built a hood,
stand, disinfected plants, and I forget whatever else based on your info.
I just had one minor issue with the appendix of the PMDD article (yes, I've
been here that much).  The final table has g/L of nutrients and then a %
total column.  That percent total column is hell of confusing, given that
its the g/L which is actually reported on fertilizers (I was unable to get
either of the ones mentioned in the article, because the Canadian source
involved brokeraage, etc. and the pennsylvania company seems to not use
that number any more.  I have no idea if you update info at that level, but
I thought I should bring these to your attention, in case you didn't have
enough to do.  Many, many, many thanks for your site,

Doug

Doug Karpa-Wilson

Department of Organismic and     		Department of Biology
              Evolutionary Biology			Indiana University
Harvard Unversity				Jordan Hall
16 Divinity Ave.
Cambridge, MA				Bloomington, IN  47401



Trace element supplementation

by krandall/world.std.com
Date: Sat, 03 Apr 1999

James Purchase wrote:

>"PMDD can work very well - IF you know what you are doing. If you DON'T know
>what you are doing, it is better to stick with commercial preparations which
>are designed for aquariums."

Tom Wood wrote:

>The trouble is, commercial preparations that don't disclose ingredients
>leave you in a state of perpetually never knowing what you are doing,
>whether you think you do or not.  I moved quickly to PMDD to overcome that
>commercially enforced state of ignorance.  At the time I didn't know any
>more about what I was doing than what I gleaned from the Sears-Conlin paper.
>Plant fertilizer is really simple stuff once you know what is in each
>component of a fertilizer regime and why it is there.  

The thing that amuses me about this sort of statement is that I have yet to
hear of any of the PMDD advocates actually formulating their own trace
element mix.  People simply use whatever hydroponic mix they can get their
hands on, whether the ratios of different elements make sense for our
purposes or not, and use it.  While it makes a great deal of sense to me to
fine tune the dosing on N, P & K based on your own tank conditions,
(calcium and magnesium too, depending on your local water supply) to think
that you are doing things "more scientifically" by mixing your own
hydroponic trace element mix with distilled water is only fooling yourself.
 Now if you're doing it because you want to save money, or because you
can't find a well balanced commercial trace element supplement in your
area, those are legitimate reasons.  But if you're using _anybody's_ "trace
element mix" and you think you are "fine tuning" in any way that you
couldn't with a commercial product, your just fooling yourself.


PMDD calculations, 2nd time

by Paul Sears <psears/nrn1.NRCan.gc.ca>
Date: Tue, 16 Mar 1999

	The calculations look reasonable, but more complicated than
necessary - if you are trying to get the same amount of iron with
an mix with a lower concentration (3.35% vs 7%) you just need 
to add 7/3.35 times as much.

	Bear in mind though, that the amounts of materials in "PMDD"
are intended as a rough guide, and that some experimentation is to
be encouraged.  I was amused to see the other day that someone thought
that what Kevin and I wrote was not to be taken as gospel.  We never
intended it to be taken that way.

- -- 
Paul Sears        Ottawa, Canada


gluconate and other K sources

by "Roger S. Miller" <rgrmill/rt66.com>
Date: Mon, 28 Jun 1999

On Mon, 28 Jun 1999, Robert H wrote:

> I find this very interesting because I have been adding p.gluconate to a
> very densly planted tank with high intensity lighting, but have
> suspected that I also have created a high BOD. But I am confused as to
> what form of K I should be adding. I dont want to add nitrate...so that
> leaves sulfate? Murate of Potash? Is gluconate, gluconate? Is this the
> same stuff in Seachems Flourish products?

One problem with adding gluconate for potassium is that you end up adding
quite a lot of gluconate to get the potassium you need.  If you add enough
potassium gluconate to get 5 mg/l of potassium then you also are adding 25
mg/l of gluconate (assuming you're adding pure K-gluconate and there's no
extra gluconic acid or other gluconates in the mix).

I don't have any background info on the normal BOD or COD in planted tanks
so I can't say whether or not this is a lot, but it's certainly some and I
suspect that it is a lot.

I don't think this is much to worry about if you're using iron gluconate
tablets in the substrate once in a while, and it probably isn't a problem
with fertilizer solutions with gluconate like Flourish Iron, but if you're
using it to add large amounts of something then you might want to be
concerned.

It has been mentioned here that chelating agents can bind with magnesium
and calcium.  If that's true and your water is very soft then it may not
be a good idea to add large amounts of potassium gluconate to your water.
The gluconate may tie up the small amount of calcium and magnesium
available and exaggerate any deficiencies you might already have.  The
calcium and magnesium would be released later as bacteria attack the
gluconate, but that could take a while.

As to other sources of K, potassium nitrate is the evident choice if you
want to add nitrogen as well as potassium.  Otherwise you could use either
potassium sulfate or potassium chloride more-or-less interchangeably.
It's probably best to use whichever will create a balance of ions in your
tank - if your water is high in sulfate or if you're already adding
something with sulfate, then you might want to use potassium chloride.  If
your water is high in chloride or you're already adding chloride with
something else then you may want to use the sulfate.  All else being
equal, the chloride would cause a smaller increase in total dissolved
solids than the sulfate.

Potassium bicarbonate would be an interesting alternative, but I don't
know that it is readily available.


Roger Miller


PMDD ingredient source

by Chuck Gadd <cgadd/cfxc.com>
Date: Wed, 29 Nov 2000

I just found a place that looks to be a good source for pmdd stuff.

The place is www.yardgeek.com.   I just placed an order there, so I'll
report the quality of service once the product arrives.

First of all, they carry Green-light stump remover.   But, even
better, they sell Potassium Nitrate, by the pound, for $1.48 per
pound.    They also sell Muriate of Potash, which is Potassium
Chloride.  This is the form of potassium used in many of the potassium
additives.    4 pounds!  is $2.98.

And if anyone plans on using Profile Clay Soil Conditioner or Profile
Aquatic Plant soil, check this out:  They've got one product labeled:
Turface Regular Soil Amendment, which sounds from the description to
be just like Profile Clay Soil conditioner.  And 20 pounds is $4.99.
But even better, they sell Turface MVP, which has been reported to be
the same thing as profile, $7.95 for a 50 pound bag.

Shipping costs seem reasonable, I just ordered 4 pounds of potassium,
and 1 pound of Potassium nitrate, shipping charge (UPS Ground) was
$5.90.   (more than the cost of the product, but the total price isn't
bad, and it's more than enough to last a long time)

If you are looking for the potassium chloride on their site, search
for Potash. 

- --
Chuck Gadd


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