# [Wet Thumb Forum]-Iron



## George Willms (Jul 28, 2004)

Posted this in a different forum, but then thought I might be better off asking here. I have access to a concentrated solution on ferric ammonium sulfate and was wondering if that would be suitable for use in dosing for iron. I know that in general ferrous iron is more easily used by plants, but how much of a difference would this make. Also, from my calculations, one drop (about 0.03 g) would raise iron levels by 0.1mg/L for every 10 gallons. I could also get dry ferrous gluconate and make a solution out of that, but it would not be as concentrated. Any input, suggestions, or recommendations would be greatly appreciated. Thanks.

George


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## George Willms (Jul 28, 2004)

Posted this in a different forum, but then thought I might be better off asking here. I have access to a concentrated solution on ferric ammonium sulfate and was wondering if that would be suitable for use in dosing for iron. I know that in general ferrous iron is more easily used by plants, but how much of a difference would this make. Also, from my calculations, one drop (about 0.03 g) would raise iron levels by 0.1mg/L for every 10 gallons. I could also get dry ferrous gluconate and make a solution out of that, but it would not be as concentrated. Any input, suggestions, or recommendations would be greatly appreciated. Thanks.

George


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## Roger Miller (Jun 19, 2004)

George,

Unchelated ferric iron will form ferric hydroxides when you add it to water that isn't highly acidic. Ferric hydroxides are not available to plants. Ferric ammonium sulfate is not a chelated iron compound.

Given those two options, you are probably better off using ferrous gluconate. Seachem's Flourish Iron is Ferrous gluconate.


Roger Miller


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## George Willms (Jul 28, 2004)

Thanks much Roger. One further question for you. Which would be better to use ferrous gluconate or ferric EDTA. Thanks.

George


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## Roger Miller (Jun 19, 2004)

George,

Ferrous gluconate and ferric EDTA can both be used. They behave very differently so must be used differently. It is probably best to select one or the other based on how you want to use it.

Ferrous gluconate is biologically available and tends to break down or get used fairly quickly. It is best used in frequent, small doses, i.e., every other day or so works fine.

Ferric EDTA is not biologically available and breaks down at a rate that I think is determined mostly by the lighting. It provides a low level of biologically available iron while it breaks down. It can be used in large doses spaced over longer periods of time. Some people use iron test kits to manage their ferric EDTA levels.

Personally I prefer ferrous gluconate. The process through which plants get usable iron from ferric EDTA is a little too mysterious for me.


Roger Miller


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## George Willms (Jul 28, 2004)

Thanks Roger...

so when I get my straight ferrous gluconate, do you have any idea of how dilute a stock solution I would need to add 0.1mg/l per mL od solution to each 10 gallons? Thanks again.


George


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## Roger Miller (Jun 19, 2004)

George,

To get 0.1 mg/l in a 10 gallon tank you would need to add 3.8 mg of iron. That is given by:

0.1 mg/l x 10 gallons x 3.8 liters/gallon = 3.8 mg

To do that with a dose of 1 ml of stock solution the stock solution would have a concentration of 3.8 grams/liter of iron. That is given by

3.8 mg/1 ml = 3.8mg/ml = 3.8 grams/liter

A little search on the web gives me the molecular weight of ferrous gluconate at 446.2. Iron has a molecular weight of 55.84, so ferrous gluconate is 12.5% iron.  Put another way, 8 grams of ferrous gluconate contains 1 gram of iron.

To get a solution that is 3.8 grams/liter iron, it would need to have a ferrous gluconate concentration of 30.4 grams/liter of ferrous gluconate. That is given by

3.8 grams Fe/liter x 8 grams ferrous gluconate/gram Fe = 30.4 grams ferrous gluconate/liter

Which is real useful if you have access to a good scale.

The same web search told me that ferrous gluconate has a solubility at room temperature of 100g/liter. If you don't have a good scale then you can get close to the right dose by mixing a saturated solution, then cutting it 2:1 with water. That is, add two parts of water to 1 part of saturated ferrous gluconate solution, getting 3 parts of stock solution.

Another way to mix up the solution would be to start with ferrous gluconate tablets. These contains binders, so they aren't pure. The tablet packaging should say how much iron is provided by each tablet. That value is usually given in milligrams.

The formula is:

tablets = 1000*3.8 grams/liter / x mg Fe /tablet

For instance, if the tablets each provide 36 mg Fe then you would dissolve

1000*3.8/36 = 105 tablets

in a liter of water to get about the right concentration. A liter is a lot of stock. If you would rather mix a quarter liter at a time, then 26/tablets per 250 ml of water would be about right. I would probably just us 25 tablets/cup of water and call that close enough.

I use iron gluconate in two forms. Either mixed in Seachem products or as iron gluconate tablets that I break up and push into the substrate around plants.

The target concentration of 0.1 mg/l was established from experience using mostly ferric EDTA. I don't think you need that much if you are fertilizing with ferrous gluconate.


Roger Miller


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## António Vitor1 (Feb 2, 2003)

what about citric acid?

I put some of this stuff on my PMDD 
also with some EDTA in there...

citric acid might be a chelating agent...
what do U think about this?

I had some growth improviments when I start dosing lemon juice..


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## George Willms (Jul 28, 2004)

Hi Roger...

I have access to a very good scale at work. I would like to know where you were able to find the solubility of ferrous gluconate in water at room temp, I was unable to find it. 

If you feel that 0.1 mg/L is too high of a concentration, what would you recommend that I try to aim for? Maybe a third of that? Thanks once again.

George


George


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## George Willms (Jul 28, 2004)

Citric acid is definitely a chelating agent, as is EDTA. It seems though that the problem with chelated iron is that it is not very soluble. The whole point of a chelating agent is to bind a metal, so it is not given up too freely. 

George


George


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## António Vitor1 (Feb 2, 2003)

don't know about citric acid-Iron solubility...

but it does a great job on my tank...


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## Roger Miller (Jun 19, 2004)

> quote:
> 
> I would like to know where you were able to find the solubility of ferrous gluconate in water at room temp, I was unable to find it.


I googled to 
http://www.purac.com/products/EN-GLUCONAL%20FE-P-USP.pdf



> quote:
> 
> If you feel that 0.1 mg/L is too high of a concentration, what would you recommend that I try to aim for? Maybe a third of that?


I am not a fan of excess dosing. Depending on the size of the tank I would probably start by adding a drop or two every couple days. If that was enough I would not add more. The actual levels of biologically available iron needed by your plants is in the nanomole/liter range. You'll never be able to measure it with a hobby test kit. Even if you could measure iron at very low levels it would be difficult to determine whether the iron were in a biologically available state.

Roger Miller


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## Guest (Jun 6, 2003)

George Willms,

A bit off the topic. Are you familiar with www.njas.net. We met on 3rd thursday of each month in Meadowlands Environmental Center Lyndhurst, New Jersey which looks like you are close.

You should stop by this month.

Join as at www.njas.net


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## George Willms (Jul 28, 2004)

Well Robert...

Maybe you could just give me a ppm level to aim for. At least that way I could calculate how much I would need to add. Thanks.


George


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## Roger Miller (Jun 19, 2004)

You need to make sure that your plants get about 0.056 micrograms/liter of biologically available iron. If it drops below that now and then it's fine, because plants can store iron. In the event of occasional iron stress most of them have additional mechanisms for scanvenging iron out of their root zones.

Do you manage gardens or potted plants this way?

Roger Miler


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## George Willms (Jul 28, 2004)

> quote:
> 
> Do you manage gardens or potted plants this way?


No, I don't have any garden or potted plants. I work in a fragrance applications lab, so I have access to any chemicals that would be used for any sort of cosmetic purpose and it just so happens that ferrous gluconate is sometimes used as a skin protectant. I knew it was an ingredient in Flourish iron, so I thought that if I could save a few bucks and make my own, then why not.

George


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## wetmanNY (Feb 1, 2003)

We animals use iron to manufacture hemoglobin, but plants only use a few molecules of iron as catalysts in some enzymes. I think the same molecules of iron are used over and over in this way.

Plants store iron because they can't help taking it up but need to protect themselves from iron's toxicity.

Has any known aquarium actually suffered from iron deficiency? Iron is so reactive it disappears within hours. Aquarists imagine that plants have "used" it.

This whole *ferromania* was started by the Dupla guys in _The Optimum Aquarium_...

If I'm detecting Roger Miller's skeptical reserve about iron dosing-- I second it heartily!


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## Guest (Jun 7, 2003)

Ferromania-
There's a word for you.
I will not give a level of iron either but my dosages are likley higher than most.

I'd read 0.7ppm from a feller that sold trace mixes and laterite.Most folks seem to have been stuck with 0.1ppm from the PMDD ,method and try to maintain a residual. I've been dosing far outside that range with a number of iron chelating agents.

I dose know products like Flourish or TMG etc about every 3 days by volume of the trace mix to the tank volume. This works much better than any test kit reading. 
I usually dose around 5mls per 20 gallons 3x a week at high light with good growth and plant mass. This is about the max uptake or the min amount needed to be added and still have good healhty growth.

This was determined by maintaining the other macro nutrients and CO2 levels in a good range and also by adding lots of light. Adding more and more traces until there is no added benefit for the plants. Beyond this amount, you are wasting the trace/iron mix.

Some claim to find algae issues with high iron/traces but I have not seen this due to trace/iron additions. I've routinely over the years doubled the above dosade and never had anything romtely like a bloom.
Nothing at all happened. 

Try and make the concentration to match the Flourish iron product. But you'll also need the other traces, not just iron. 
It might not be any cheaper in the end for you since you'll also need to get this.

Regards, 
Tom Barr


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## tsunami06 (Feb 6, 2003)

I have had a 20 gallon long experience iron
deficiency. At nearly 4 w/g and plenty of CO2,
PO4, NO3, K, etc some plants did not do well.
I was dosing 5 mL three times a week of Flourish Iron and 5 mL three times a week of
Flourish Trace. My Didiplis diandra would grow
for week, stop, turn white at the apex, and
crinkle. Necrosis spots would appear on the
newest leaves. Rotala wallichii would keep
stunting no matter what I did. Raising the
Flourish Trace had no effect. Only when I raised the amount of Flourish Iron to 5 mL
four times a week did I see an improvement.

My Didiplis diandra suddenly went through a
growth spurt, became larger, had shorter
internodes, and turned bright orange. My
Rotala wallichii now grows perfectly with
decent pink coloration -- no stunting. All
my plants in general seem to have improved and
are growing much larger leaves. The tank seems
to have more 'sparkle.' I am now a serious
believer that iron/traces are key nutrients
for success in high light tanks using PCs/metal
halides.

Remember that iron is also in cytochromes,
an important protein in photosynthesis. Iron
molecules could not be completely recycled, if not the leaves that would show the deficiency would be the older leaves. I don't think iron is a very mobile nutrient.

Just a few thoughts,

Carlos

-------------------------
"If you hear a voice within you say 'you cannot paint,' then by all means paint, and that voice will be silenced." -- Van Gogh


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## Roger Miller (Jun 19, 2004)

wetmanNY,

The usual symptom of iron deficiency is interveinal chlorosis in new leaves. Several other nutrient deficiencies generate the same symptom, so the symptom is not diagnostic.

I have treated plants with those symptoms by placing bits of iron gluconate tablets into the substrate below the plant. The treatment cured the deficiency. That leaves two possibities. Either it was an iron deficiency or it was a deficiency in some other trace element that was present in the tablets at a sufficient concentration to cure the deficiency symptom.

Just the same, I think the online aquarium community places far more emphasis on iron than is justified by its status as a nutrient.

Carlos,

The symptoms you list aren't typically listed as symptoms of iron deficiency. Iron deficiency causes interveinal chlorosis that appears initially on new growth. 

The lighting level in your 20 gallon is higher than in either of my 20 gallon tanks, but your dosing levels are a 5x-10x higher. And I figure that I overdose my tanks.


Roger Miller


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## George Willms (Jul 28, 2004)

I was also wondering if anybody had any experience with using something to preserve their dosing formulas. I'm not sure what would be ok to use as a preservative. I tried benzoic acid, which is listed on some manufacturer's ingredients lists, but found it to be almost impossible to get into solution. I have access to any number of methyl- and ethyl-parabens, any help or recommendations on this part are greatly welcomed. Thanks.


George


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## tsunami06 (Feb 6, 2003)

> quote:
> 
> Carlos,
> 
> ...


The interesting thing though is that I had this
iron deficiency for months without being able
to figure it out. Before anyone here thought
that was K+ was a problem in their tanks,
I completely cut out K+ dosing in my 20g
for a couple weeks. The plants that were
suffering did not improve.

I also tried lowering nitrate, since IME
wallichii liked it really low. It just kept
on stunting. I also tried keeping the phosphate
on the higher side for a time (~1ppm), and
still nothing. But I thought I was adding
more than enough iron...

The iron was the last nutrient I played with
and the only one to fix the problem. Since
the leaves are so thin or fine, perhaps
the fact that it is iron deficiency isn't
so obvious? Looking back, anything in the Rotala genus did not do well in that tank until
recently. Hemianthus micranthemoides, Anubias,
Marsilea, Ludwigias, Hottonia grew just fine
without the extra iron boost.

Carlos

-------------------------
"If you hear a voice within you say 'you cannot paint,' then by all means paint, and that voice will be silenced." -- Van Gogh


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## George Willms (Jul 28, 2004)

I had a new iron question. What would be the result of having too much iron, say dosing too much Flourish iron?

George


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## Roger Miller (Jun 19, 2004)

The iron toxicity symptom I've read about in plants are excessive "greeness" and occasionally deficiency in manganese or zinc.

The other possible symptom of Flourish Iron overuse is a cash deficiency in the plant owner.

Roger Miller


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## George Willms (Jul 28, 2004)

I'm using my own formulation that is similar to flourish iron, so I'm not worried about cash deficiency from that. Could it lead to any sort of algae becoming prominent though? I guess that is my main concern.

George


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## Roger Miller (Jun 19, 2004)

PMDD tradition holds that excessive iron levels favors hair algae. YMMV.

Roger Miller


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## George Willms (Jul 28, 2004)

YMMV??? I was wondering if it might favor hair algae. I had a bloom of it recently and I'm cutting back on my iron dosing to see if it helps.

George


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## Roger Miller (Jun 19, 2004)

YMMV=Your Mileage May Vary.


Roger Miller


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