You are at The Krib ->Plants ->Fertilizer [E-mail]



  1. chemicals and dosing
    by Neil Frank <> (Fri, 04 Apr 1997)
  2. Cation Ratio's - How Important is It?
    by "James Purchase" <jpurch/> (Tue, 8 Dec 1998)
  3. RO recon
    by "Roger S. Miller" <rgrmill/> (Mon, 2 Aug 1999)
  4. RO recon
    by Steve Pushak <teban/> (Tue, 03 Aug 1999)
  5. Adventures in Dosing-Pump Fertilization
    by Jared Weinberger <jweinberger/> (Fri, 23 Jun 2000)
  6. Re:iron and TMG etc
    by Thomas Barr <tcbiii/> (Fri, 31 Aug 2001)

chemicals and dosing

by Neil Frank <>
Date: Fri, 04 Apr 1997

>Date: Thu, 3 Apr 1997 23:58:12 -0500 (EST)
>From: Tim Mullins <>
>Subject: PMDD: Sources and Doses Round 2
>In response to questions on PMDD, here's
>an update on my post on where to buy PMDD
>(poor man's dosing drops) and how to use it.
>Hope this helps (many thanks to those who made
>comments, sorry this has gotten so dang long):

Thanks Tim for the complete and interesting post. I have set it aside for
study when I get the time. In the meanwhile, I thought I would share my
draft writeup that is related to the general concept of dosing -- involving
trace element mixes, commonly available chemicals and use of tools like
measuring spoons.  I thought people might find it useful (I hope the columns
are not messed up too badly and that people do not take offense to the use
of "American" units <g>)

- --------------------------------------------------------------------------
   Determining the Concentrations of Chemicals Added to the Aquarium
Chemicals are often added to aquariums to provide food for plants or to
establish other chemical parameters. Added nutrients may be macro nutrients
(e.g. potassium (K), magnesium (Mg), calcium (Ca)) or trace elements. In
some cases, Nitrogen (N) may also be needed when the plant's requirements
exceed the available supply or when plant growth is intentionally pushed.
The chemicals may also be needed to correct nutritional deficiencies. In
addition, bicarbonate levels in the aquarium water are often modified to
achieve desired pH. With a pH controller, this will help establish
particular CO2 concentrations in tanks with CO2 injection. 

Sometimes chemicals are provided through commercially prepared nutrient
solutions, pH buffers or KH "builders."  However, the aquarist may want to
create his or her special brews to replace or supplement the commercial
products.  Fine tuning may be useful in order to account for one's local tap
water and particular aquarium conditions. This discussion does not
extensively focus on the specific circumstances indicating when and why one
adds these chemicals to the aquarium. This has been discussed elsewhere.
Instead, the focus here is on determining the concentrations and achieving
target levels.

Chemicals for the aquarium can be found as dry ingredients (crystals or
powders), or in liquid form (solutions). Many useful chemicals can be found
in the grocery or local pharmacy. The dosing approach described here can
involve a concentrated "stock" solution or dissolving the chemical in a
small amount of water and then adding the potion directly to the aquarium.
Applications are included for adding macro nutrients (N, K, Mg, Ca),
achieving target iron concentrations using trace element powders and
increasing carbonate hardness (KH) or general hardness (GH). Avoidance of
excess concentrations is discussed.

Terminology and Computational Procedures
Concentration units of chemicals in the aquarium are often expressed in
parts per million (ppm), for example milligrams of nitrate per 1,000,000 mg
of solution. (A liter (L) of water weighs 1000 grams (g) or 1,000,000 mg,
and so one ppm is one milligram per liter). One ppm is also the same as 1 g
(1,000 mg) per 1,000 L.

For Americans and others who may not be comfortable with the metric system
or still think about their tanks in terms of U.S. gallons, concentrations
can also be expressed in other units. Multiples of 10 gallons is a useful
volume.  For 1 gram of soluble material, the concentration in 10 gallons of
water can be determined by simple arithmetic. Because 10 gallons is 37.85 L,
then 1 gram (g) / 10 gallons is 26.4 ppm.  For 50 gallons, one gram creates
5.3 ppm.

Often we are not interested in achieving the concentration for a particular
chemical compound (like table salt, NaCl), but separately for its chemical
constituents or ions (i.e., the Na+ or Cl-). This is also true for the
components of nutrient salts, like Sodium Nitrate (NaNO3) or mixtures of
trace elements. In general, specific elements or ions represent a fraction
of the entire chemical. For example, Chloride represents 61 percent of the
weight of table salt. 

If the concentration of Fe in the trace element. mix is 7 percent, then one
gram of trace element powder added to 50 gallons of water is simply (0.07) x
(5.3) = 0.37 ppm. 

We can also work backwards to determine the amount of chemical needed to
achieve a particular target concentration. With trace element powders, iron
is often used as the indicator variable and tells the aquarist if all other
trace elements are in proportion. For this purpose 0.1 ppm Fe is used.

To determine the achieve 0.1 ppm Fe from the trace element powder, the
number of needed grams, G, in our example volume of 50 gallons of water is:

                  (0.7) x (5.3) x G = 0.1,      so,  G = 0.27

In other words, approximately 1/4 g of this trace element powder is needed.

The same principle can be used to determine the amount of any compound (e.g.
table salt) needed to achieve a desired concentration of any ion or element.

Example Chemical Concentrations
The following table shows the percentage of various ions in different
compounds and the resultant concentration for different constituents from
dissolving 1 gram of the compound in 50 gallons of water.
Compound        ion  or         percent (p)     concentration (ppm) 
                element        of compound      resulting from
                                                1 g in 50 gal (189 L)
Sodium Nitrate    nitrate               73              3.9
(Nitrate of Soda)  nitrate N            16              0.9
NaNO3              sodium               27              1.4

Ammonium Nitrate  nitrate               78              4.1
NH4NO3            nitrate N             17.5            0.9
                  ammonium              22.5            1.2

Ammonium Chloride   ammonium            34              1.8

Sodium Bicarbonate   bicarbonate        73              3.9
(Bicarbonate of Soda)     sodium        27              1.4

Potassium Chloride  potassium           52              2.8
(Muriate of Potash)  chloride           48              2.5

Potassium Nitrate  potassium            39              2.1
KNO3              nitrate               61              3.2

Calcium Carbonate  calcium              40              2.1
CaCO3             carbonate             60              3.2**

Magnesium sulfate magnesium             10              0.5
(Epsom salt)     sulfate                39              2.1
MgSO4*7H20        water                 51              2.7
- --------------------------------------------------------------------------
* concentration = 5.3p / 100
**Note: the carbonate is converted into bicarbonate after the CaCO3 dissolves.
- --------------------------------------------------------------------------

How to Measure a Particular Amount
Not everyone has a gram scale, and sometimes it may be more convenient to
prepare concentrated stock solutions and then add a portion to produce the
desired (diluted) concentration. On the other hand, precisely knowing the
resultant concentrations is not critical and therefore some standard
measuring devices (like fractional teaspoons) can be very useful to
approximate these small weights.  Sometimes, the chemical comes in nicely
pre-packaged amounts, like Calcium tablets  (Dietary supplement,  pure
calcium carbonate), but generally teaspoon measures are sufficient. I have
discovered that for most chemicals, 1/4 teaspoon (t) = 1 to 2 grams. Here
are a few example concentrations resulting from 1/4 teaspoon of different
compounds and from calcium tablets.
Compound                Weight (g)              Element Concentration (ppm)
                        per 1/4 tsp.    or ion  of 1/4 t in 50 gallons
- ----------------------------------------------------------------------
sodium nitrate          1.8             NO3-            7.0

sodium bicarbonate      1.3             HCO3-           5.1

ammonium nitrate        1               NH4+            1.2
                                        NO3-            4.1

potassium chloride      1.5             K+              4.2

Potassium nitrate       1.4             K+              2.9
                                        NO3-            4.5

Magnesium sulfate       1.35            Mg++            0.7
(hydrate)                               SO4--           2.8
- -------------------------------------------------------------------
Calcium carbonate                       Ca++            3.2*
 * (600 mg Calcium tablet)              CO3--           4.8*
Note: the carbonate is converted into bicarbonate after the CaCO3 dissolves.
- -------------------------------------------------------------------

Molarity of Solutions.
   Preparing a stock solution is another way to precisely provide the
amounts of material to create concentrations in the aquarium. Stock
solutions are often described in terms of molar concentration. This is
determined from the atomic weight. For example, potassium has an atomic
weight of 39.1 - one mole of potassium would weigh 39.1 grams and a 1 molar
solution of KCl is 39.1 g K per liter.

  With solutions, milliliters (mL) are a standard unit of measurement. These
are found, for example, as the markings on the vials that come with some
aquarium test kits. (By the way, one mL is the same as one cc - a cubic
centimeter).  Furthermore, the molarity of a solution is a standard way to
describe ionic concentration.  A one molar solution of a molecule (or ion)
is a solution that contains the molecular (or ionic) weight, in grams,
* of that molecule (or ion) per liter of solution.  Therefore, measurements
in milliliters of a molar solution is another convenient way to produce a
specific amount of material in milligrams.  One milliliter of a one molar
solution contains one thousandth of the amount of material in a mole. For
example, one mL of a one molar solution of KCl contains 0.0391 grams or 39.1
milligrams of K.

   Here is an example: Five mL of 1 molar KCl would be 0.005 liters, which
would contain 0.005 moles. Adding this KCl to 10 gallons of water (37.8
liters), we now have 0.005 moles K in 37.8 liters, or 0.000132 moles per
liter.  Potassium has an atomic weight of 39.1, and so one mole of potassium
would weigh 39.1 grams. Multiplying the 0.000132 moles per liter times 39.1
grams per mole gives 0.00517 grams per liter or 5.17 milligrams K per liter
or 5.17 ppm. This procedure is an alternative to directly adding 0.195 g of
K (0.005 moles) or 0.375 g KCl  (also 0.005 moles). In 50 gallons, 5
millimoles KCl produces approximately 1 ppm K.

Concentrations Resulting from Trace Element Powders.
A trace element mixture contains many different elements. The labels usually
indicate their composition in terms of their percentage by weight. For
example, PP Ltd trace element powder has 6 different nutrient trace elements
as presented below. Knowing their weight by percent allows a direct
calculation of the concentration resulting from adding a specific weight per
unit volume of water.

As an example, the following concentrations would result from 1 gram (and
0.25 grams) in 50 gallons of water:

- ---------------------------------------------------------
            Percent          Concentration (ppm)                        
Element   by weight   1 g per 50 gal.  0.25 g per 50 gal.
- ---------------------------------------------------------
Fe              7               .37        0.1
Mg              2               .11        0.03
Zn              0.4             .02        0.005
Cu              0.1             .005       0.001
Bo              1.3             .07        0.02
Mb              0.06            .003       0.001
- ---------------------------------------------------------

Similar tables can be produced for different volumes, including stock

If one wants to use the powder directly and not have to worry about storage
problems associated with the prepared solution, I discovered that the
measure that came with the Dupla test kits (e.g. iron kit) corresponds to  ~
0.1 g of trace element powder. Therefore, 2 ½ measures in 50 gallons of
water will yield the desired Fe and other concentrations. A more precise
approach would utilize a stock solution and then a specific number of
milliliters of solute can be decanted for each application.  Let's say that
one wants a solution of 5 milliliters to contain 0.25 g of trace element
powder. This means that one mL would contain 0.05 g and 1000 mL would need
50 g. 

German, English and American Units for Hardness
There is a lot of confusion caused by many different units to measure
hardness.  Sometimes hardness is expressed in terms of degrees. In the UK, 1
degree of hardness is equivalent to one grain of CaO per Imperial gallon of
water. In Germany, 1 deg (dH) is equivalent to 10 mg CaO per liter, while in
the U.S. water hardness is expressed in ppm of CaCO3.  This is further
complicated by the distinction between general hardness (GH) and carbonate
hardness (KH). General hardness considers both permanent hardness caused by
all calcium and magnesium compounds including their sulfates and chlorides
and temporary or carbonate hardness based on  the carbonates.  Strictly
speaking,  GH is always greater than or equal to KH. However, since KH is
measured as a bicarbonate, one can appear to have KH without any Calcium or
Magnesium in solution.

Here are some conversions:

1 degree of carbonate hardness (KH)  =  17.9 ppm of carbonate
                                          (measured as  CaCO3)

1 degree of general hardness (GH)   =   7.14 ppm Calcium
                                          Or 17.9 ppm of CaCO3

Chemicals Used to Increase Carbonate Hardness (KH) and General Hardness (GH)
Carbonate and general hardness can be increased by using several chemicals
which are available in grocery stores, pharmacies and the aquarium shop.
These include Calcium Carbonate tablets (sold as a dietary supplement) and
sodium bicarbonate (baking soda).

        One g of CaCO3 yields 5.3 ppm in 50 gallons, 
        so 3.4 g becomes 17.9 ppm or 1 KH.

CaCO3 tablets sold in the pharmacy as a dietary supplement are 1.5 grams;
thus 2 1/4 tablets are needed to raise one degree of KH.  The tablets are
pure calcium carbonate and dissolve very easily. I put them in a one liter
bottle of water to create a CaCO3 suspension. When this chalky liquid is
poured into the water, it will take several hours before it will clear. This
is because it must react with CO2 to form the very soluble bicarbonate. 

A solution of 17.9 mg/L of CaCO3 in water gives KH of 1.  This
solution contains 0.179 mM Ca++, but does not contain any significant CO3--,
because this is converted to HCO3-, of which two are formed from each CO3--,
giving 0.358 mM HCO3-.  We thus want 0.358 mM NaHCO3 in the solution.  The
molecular weight of this is 84, so we want 30 mg/L sodium bicarbonate. In 50
U.S. gallons, this amounts to 5.68 g or a little more than 1 teaspoon (1.1 t).

- -------------------------------------------
                                Amount to achieve 
                                1 degree KH in 50
Compound                        Gallons of water
- -------------------------------------------
Sodium bicarbonate      1.1 teaspoon
Calcium carbonate       2 1/4 tablets
- -------------------------------------------

How to Increase Calcium Concentration and GH
Corresponding to the discussion of CO3, one g of CaCO3 yields 2.1 ppm of Ca
in 50 gallons of water. So, adding 2 Calcium tablets (3 g) will increase the
Ca concentration by 6.4 ppm. This is a little less than 1 degree of general
hardness. As with carbonate hardness 2 1/4 tablets are needed to get 1
degree GH. You will note that an increase of 1 degree of carbonate hardness
will also cause an increase of one degree of general hardness.

Concluding Remarks
Adding chemicals should be done with caution. Unless nutrient deficiencies
are known or specific target concentrations are desired, these actions are
not needed and could even be harmful.   Monitoring water chemistry is
useful. This can be done by observing the behavior and appearance of the
plants and fish (i.e. looking for symptoms of deficience or toxicity) or by
performing chemical testing.  There are many commonly available general (pH,
KH, GH) and chemically specific tests (e.g. Ca, CO3, NO3, NH4, N, Fe) which
will ensure a stable system.  Some elements like Potassium (K), however, do
not have common home test kits, so increases beyond the uptake by plants and
fish does warrants some attention. There is also concern about relative
imbalance in concentrations because plants have the ability to consume more
chemical than they need and high concentrations of one element (e.g. Mg) can
block the uptake of other elements. Inhibition of nutrient uptake does not
appear to be a problem with other macro nutrients (N, P, K). Nitrogen can be
added in terms of Ammonium or Nitrate compounds. Although plants prefer the
former, the use of the latter is probably wiser, because of potential
ammonia toxicity to fishes at relatively low concentrations.

The directions for commercial nutrient preparations make assumptions about
fish load, amounts of fish food, plant density, growth rate and tap water
chemistry.   Nevertheless, they do provide an indication of safe
concentrations, both in quantity and in their relative amounts.  Aquarists
are advised to research their own water chemistry together with  available
sources of information before they haphazardly start to dump stuff in the
tanks.  One excellent way to reduce the chance of overdosing from routinely
adding chemicals, however, is to add them at the time of a water change and
at a rate less than the desired concentration. Although many chemicals are
partially or completely consumed by actively growing plants, it is still
theoretically possible that none may be used up between water changes.
Therefore, lacking precise information on chemical uptake, adding chemicals
should (1) generally accompany an X percent water change, (2) be done when
the replacement water is lacking that substance, and (3) at a rate equal to
X percent of the desired target increment. The latter is needed to ensure
that concentrations do not increase.  For example, if the starting
concentration is 25 ppm and 5 ppm are added with each 20 percent water
change, then there will not be any increase in the final concentration.
Knowing the target concentration is not always easy to ascertain.   The
range of safe concentrations is not always readily available. More
information is desired on the consumption rates in the aquarium  and
desirable target concentration levels - both for individual chemicals and
for their combinations.  Differences between hard and soft water situations
are also important.

Incremental concentrations of 1 ppm potassium and 0.5 ppm magnesium are
utilized in some commercial preparations for weekly dosing together with
biweekly water change.  Potassium can probably be safely increased a few
fold.  Nitrogen and phosphates are often omitted from commercial
preparations for aquarium plants, but aquarists have empirically determined
that 1-5 ppm NO3 are safe added amounts for nitrogen deficient tanks.  As a
rough rule of thumb, these amounts would correspond to small quantities of
dry chemical: 1/4 tsp Potassium Chloride (Muriate of Potash) in 200 gallons
of water, 1/4 tsp Magnesium Sulfate hydrate (Epsom Salt) in 70 gallons of
water and 1/4 tsp of Sodium nitrate (Nitrate of Soda) in 70 gallons of
water. Alternatively, the K and NO3 can also be roughly achieved by 1/4 tsp
in 150 gallons of water.  Assuming the replacement water does not have any
of these macro nutrients and there are no other suppliers of these
chemicals, then dosing with water changes ensures that long term
concentrations stay relatively low (0.5 to 2.5 ppm for Mg, 1-5 ppm for K and
5 to 25 ppm for NO3).  With actively growing plants, the steady state
concentrations will invariably be much lower.

        Thanks to Paul Sears for a general review and advice on carbonate
chemistry; and to Paul Krombholz for providing the example calculation of
ppm and molarity of solutions.

Neil Frank      Aquatic Gardeners Association         Raleigh, NC
      The Aquatic Gardener - journal of the AGA -  now in its seventh year!!

Cation Ratio's - How Important is It?

by "James Purchase" <jpurch/>
Date: Tue, 8 Dec 1998

Re-reading Dupla's "Optimum Aquarium", I noticed once again the differences
in ionic species ratios between what Horst and Kipper measured in their
"mains water" and water from a stream in South Thailand (Cryptocoryne area).

		Mains		Cryptocoryne
		Water		Area
Ca/Mg		83%		27%
Na		14%		56%
K		3%		17%
HCO3		50%		41%
SO4		30%		8%
Cl		20%		51%

Given the differences in local water supplies, I'm sure that people living
in different areas would have "Mains Water" which might deviate from that
which Horst and Kipper measured and the ratios might be different. But how
important is it that the relative ratios as measured in Nature be duplicated
in an aquarium?

For example, I use R/O water in my tanks (TFC membrane), so I'm pretty sure
that my source water is very low in TDS. To reconstitute the water and make
it suitable for use in my aquariums, I add Kent R/O Right and Sodium
Bicarbonate (for Alkalinity). As Kent does not give any information as to
the ratios of the various elements in their products and test kits for Na
and K are not readily available, does anyone have any idea of the "type" of
water (i.e. the species ratio) that results from the use of R/O Right (or
any other commercially available reconstitution mixture) with R/O water?

Or does it really not matter if the ratio of the cations in our tanks and in
a tropical stream is different, given sufficient Ca, Mg and K for plant

James Purchase
Toronto, Ontario

RO recon

by "Roger S. Miller" <rgrmill/>
Date: Mon, 2 Aug 1999

On Mon, 2 Aug 1999, Kevin Zippel wrote:
> On 12 June 1999, Roger Miller posted a great note on reconstituting RO
> water (copied at the end of this message).  In this post, he makes
> reference to an earlier post by Neil Frank, Paul Krombholz, and Paul
> Sears, which contained similar info on chemical dosing.  I can't seem to
> find the original post -- perhaps it's under a PMDD instead of an RO
> subject line, in which case I'll never find it!  Can anyone point me in
> the right direction?

It's at

> One thing about Roger's recreation of the formula
> that confuses me (I'm no chemist!) is how those ingredients can generate
> a GH of ca. 3d.  Using recommendations posted numerous times on this
> list, we know that 2 teaspoons of calcium carbonate will raise 13
> gallons by 4d (both KH and GH).  Roger's formula requires 6600 mg of
> calcium carbonate (6.6g, approx. 1 tsp) for 50 gal.  That's 1/2 the
> chemical dose for 4x the water, or 1/8 the previously recommended dose,
> which would seem to then yield 0.5 d GH.

I don't really know the origin of your dosing advise, but in order for 2
tsp of CaCO3 to create 4 dGh in 13 gallons of water it would have to weigh
1.76 grams per teaspoon, which I think is only about a quarter to a third
of the actual weight of a teaspoon of powdered CaCO3.  By my estimates it
would only take something like 1/2 teaspoon of powdered CaCO3 to generate
4 dGH in 13 gallons of water.

You may not be a chemist, but you did a pretty good job of catching a
couple problems I had with calculating the dose from the calcium tablets.

First, the tablets described in Neil's paper contain 600 mg of *calcium*.  
I treated them as if they contained 600 mg of *calcium carbonate*.  To
contain 600 mg of calcium the tablets would actually contain 1500 mg of
calcium carbonate.

Second, I mishandled the calculation of Kh from the tablets.  To be clear
I'll state this precisely; I will assume the CaCO3 is dissolved in water
creating a solution with a high pH and that the solution will be allowed
to react with air or with added CO2 until the CO3-- ions are all reacted
to bicarbonate (HCO3-) ions and the pH drops to more reasonable numbers
(say, below 8.5).  My confusion on this point also altered the amount of
sodium bicarbonate needed to make 3 dKH.

> Granted, there is also
> magnesium in the formula (epson salt), which will contribute to GH, but
> clearly less than the calcium (as evidenced by thier final
> concentrations in mg/l, 4.64 vs. 13.95).  So where am I losing it?

The magnesium provides about 1 dGH.  The calcium should provide 2 dGH to
total 3 dGH.  

> Similarly, I don't see how KH can be ca. 3d.  We get 0.5dKH from the
> calcium carbonate, plus 2dKH from the sodium bicarbonate (if 1 tsp gives
> 4dKH to 13 gallons, as per previous recommendations, then the 2 tsp / 50
> gallons in this recipe should yield 2dKH, yes?).

According to Neil's paper, a 1/4 teaspoon of sodium bicarbonate weighs 1.3
grams, so a full teaspoon would weigh 5.2 grams (+/-, I'm sure).  5.2
grams of sodium bicarb would give 3.78 grams of bicarb.  In 13
gallons of water that's 76.7 mg/l of bicarb, or 3.5 dKH.  Two teaspoons in
50 gallons would give 2*3.5*13/50 = 1.8 dKH.  Close.

> 2.5dKH is closer to
> the predicted 3 than we got with GH, but still short of the mark.  Can
> anyone put me in touch with the original post, Neil Frank, or an error
> in my calculations?

Kevin, thanks for giving the recipes the careful review they need.  The
corrected recipes follow.

 Chemical                dose/           dose/           measurement
                         100 liters      50 gallons      unit
 epson's salt            3.5             6.5             1/4 teaspoons
 calcium carbonate       2.5             4.5             600 mg tablet
 baking soda             2.5             4.5             1/4 teaspoons
 potassium chloride      1.5             3               1/4 teaspoons

The composition (after the pH drops) should be
                         dose/           dose/           measurement
                         100 liters      50 gallons      units
 calcium                 15.0            14.3           mg/l
 magnesium                4.7             4.6           mg/l
 sodium                   8.9             8.5           mg/l
 potassium               11.8            12.4           mg/l
 bicarbonate             69.4            66.0           mg/l
 sulfate                 18.4            18.0           mg/l
 chloride                10.7            11.3           mg/l
 general hardness         3.2             3.1           degrees
                         57.1            55.0           ppm as CaCO3
 alkalinity               3.2             3.0           degrees
                         56.9            54.1           ppm as CaCO3
 Na/(Ca+Mg+K)            0.27            0.26           molar ratio
 total dissolved solids  79.8            78.9           mg/l
And of course, all the same instructions and cautions that went with the
first draft could be repeated here.

One set of comments down.  Any other?

Roger Miller

RO recon

by Steve Pushak <teban/>
Date: Tue, 03 Aug 1999

> One set of comments down.  Any other?

I found that the bulk density of powdered chemicals such as CaCO3 can
vary quite a bit. This was especially true for the chelated trace
elements which we have been getting here in Vancouver (from the same
source I believe). They have changed the formulation and the new powder
is about twice the density.

You will have an error in calculating concentrations when using
volumetric measures such as teaspoons and cups, however the target
concentrations are not at all critical. According to Paul, it makes
virtualy no difference if say the potassium concentration is 5ppm or 100
ppm so long as there is a sufficiency. What that means is that you
should dose to a high enough level that the nutrient does not end up
being used up. Obviously for iron, there are other reasons for being
concerned about the actual concentration since this nutrient and
phosphorus should be the growth limiting nutrients in solution in order
to restrict algae.

To summarize: its ok to use tsps to measure CaCO3, potassium and
magnesium salts but you should _probably_ use an accurate scale for
measuring chelated trace nutrient powders.

On other thought occurs to me: the bulk CaCO3 seems to be harder to
dissolve than the finely powdered stuff I bought from a pharmacy. I
think there's a difference in texture (particle size).

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"
 for LOTS of pics, tips and links for aquatic gardening!!!

Adventures in Dosing-Pump Fertilization

by Jared Weinberger <jweinberger/>
Date: Fri, 23 Jun 2000

Over recent months, I've had good results by both increasing the amount of
water-column fertilizers as well as dividing the dose up into three
portions throughout the day. Given also the number of ingredients I'm
using, both commercial and chemical, I decided to try a dosing pump not
only to administer the fertilizers around the clock, but also to replace
some of the evaporate from our 135-gal by diluting the fertilizers in
distilled water. Even with multiple manual dosing, I found that, e.g., the
iron concentration can drop from 0.2 to 0.1 ppm in the course of 12 hours.
Granted this is precipitation as well as uptake, but nontheless the water
concentration falls rapidly. I assume some other metal micronutrients have
a similar fate.

I checked with Greg Morin of Seachem, who felt that the combination of
products I had in mind would not adversely interact. After two negative
experiences with other brands of pumps (the Eheim Liquidoser and then the
AquaTune dosing pump were returned as both had various defects and did not
work properly). I settled on the LiterMeter made by SpectraPure. It's a
precision pump that can deliver anything up to 100 L per day. Based on both
our tank evaporate and convenience, I chose to make up a week's supply of
my fertilizer cocktail diluted with distilled water to 3.5 L. This fits
comfortably in a gallon container that I marked off in 0.5 L increments. I
dose 0.5 L per day. Some time before the end of the 6th day I change
containers and save the remaining fraction to add at the next water change.

The LiterMeter was $240, which I admit is a luxury, but then again so is
most everything for a show tank. The unit is small and very lightweight. It
can stick to any wall or surface with the supplied Velcro mounts. You
connect it with the supplied 1/4" tubing to your water/fertilizer container
(intake) and to your tank (outlet). There are two rotary digital dials. The
first (3 digits) is to set the calibration. After you have everything in
position and your pump and outlet are at the final height, you time how
long it takes the pump, set to running continuously, to fill a 500 mL
measuring cup (usually under 2 min). A little simple math and you set the
calibration dial to the amount pumped in 1 min (which was exactly 300 mL in
my case). You dial in the amount of liquid you want to deliver in the
course of 24 hr on the other dial (4 digits going up to 99.99 L), turn on
the pump, and that's it! Once you set the calibration, you can change the
amount to deliver per 24 hrs at any time -- you just turn the pump off and
on again to change to the new volume.

The LiterMeter calculates how much to deliver each time it doses, which is
at most 150 times a day. For the curious, this works out to every 9' 36".
For very small volumes (my case) it may sometimes skip a cycle since there
is a minimum it can dispense (it saves the fractional amount not dosed in
an internal buffer which, when filled, adds the extra to the next cycle).
At my small daily volume the unit actually pumps for only about 1-2 sec.
When pumping it's fairly quit and sounds like a sewing maching trundling in
another room -- otherwise it's completely silent (a flashing green light
tells you the unit is running; a red light goes on when it doses). The unit
is very accurate -- certainly more so than the felt-tip lines I've drawn on
my gallon container. I'm certainly you can get the accuracy to within a few
mL per day, but since we all have some evaporate I see little reason to try
to dose very small quantities of undiluted liquid commercial fertilizers.

The unit comes with a cut-off switch, which you can mount in your tank.
This is designed more for reef tanks where you want to keep your tank water
height at a given level (you would set the unit for a high daily amount and
it cuts off if the tank level reaches a certain point on the in-tank
rod-switch). Since I'm using the LiterMeter to dose a precise amount of
diluted fertilizer, I don't use this limit-switch.  It has a three-roller
direct-motor drive, so that the liquid you are dosing never comes in
contact with any motor parts. For that reason there is no damage if your
liquid should run out and the pump (which is self-priming BTW) runs dry.
I'm told that maintenance will be as infrequently as every 1.5-2 years,
since I'm not dosing a caustic substance. More info at 

Two tumbs up from

Jared, who has no connection with the manufacturer and whose current
cocktail is:

Seachem Flourish
Seachem Iron
Seachem Excel (just started)
Karl Schoeler's Natural Gold
Potassium sulfate
Magnesium sulfate
Boric Acid (pinch)

Shaken, not sirred.


Jared Weinberger            
______     ________

Re:iron and TMG etc

by Thomas Barr <tcbiii/>
Date: Fri, 31 Aug 2001

I add every 2-3 days the following: KNO3, PO4 source, and a trace mix(TMG,
SeaChem flourish etc). Weekly I don't get nearly as good results I feel.

 Weekly is often the range that folks change water so adding it then seem to
be easy. Adding it daily is a hassle IMO. It makes no difference in the
plant's needs or some carefully planned strategic hostile plant takeover bid
to out do the algae. I seriously doubt anyone's going to make or break any
tank issues with that one. I think adding some macro's in a decent range is
a good idea 2-3 times a week. In order to keep this range 2-3 times a week
is about what most would use unless they have a fair amount of fish(heavy
feeding) etc or high NO3/PO4/tap etc.
This dosing is for high light/CO2 plant tanks etc.

I am so skeptical of what the hell folks are really measuring when they say
iron. I went down today and spoke with a chemical engineer about that does a
great deal of work in Oceanography analysis and primary production about
iron. It was an interesting talk. I think there is a great deal of work to
be done in this area for aquariums.
Tom Barr 

Up to Fertilizer <- Plants <- The Krib This page was last updated 18 February 2002