Comparing the main ingredient in Flourish Iron to other (similar) ones....

[LabTest57]

Okay, so chelated iron can be given to plants, but it takes longer for them to consume it.

Ferrous gluconate is what Seachem uses for their Flourish "Iron" supplement for plants, which is supposebly consumed faster by plants.

Are these forms of iron compatible or at least useable for aquatic plants: Carbonyl iron, Ferrous bis-glycinate, and Ferrous sulfate?

[EDIT]: I found out recently that some people actually use ferrous sulfate instead of chelated iron. In availability vs deficiency, ferrous sulfate seems to help with deficiency, while chelates increase availability. However, to my uderstanding, Seachem's Ferrous Gluconate in Flourish Iron is actually a weak "chelate". How do we know what is chelated or not, or just a "modified" weak chelate? For fact, most human iron supplements are chelated, which makes the supplemental iron last longer. I wonder if most of the Seachem Trace mixes, for different aquatic environments that include soluble iron as a trace mineral, use a chelated FeSO4 (as most minerals are bonded with sulfates and are chelated in some way)? Actually, Equilibrium contains ferris sulfate (Fe+3), but ferrous sulfate is still more soluble (Fe+2); does solubility determine toxicity, like copper when it goes from Cu+2 to a more toxic form as Cu+?

Here are some sites that backup the claims for ferrous sulfate, which is the same as FeSO4 (as some sites include this, rather than the name) :

http://www.barrreport.com/co2-aquatic-plant-fertilization/2552-iron-pills-my-experiment.html

http://www.barrreport.com/co2-aquatic-plant-fertilization/3967-can-feso4-used-iron-supplement.html
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Also, I would like to point out that "Flourish Iron" isn't available where I live, as I've checked everywhere. Ordering online is a no-go for me, because I got some debts to pay off,etc. (bank/credit card issues). The economy down here in Florida is horrible, Seachem products cost 2x more than they used to. However, human iron supplements are cheaper, available, more concetrated (watch out for additives though), and compatible in some way for aquatic plants. Ferrous sulfate (the non-chelated brand) seems to work best for plants, which consume it rather quickly or moderately in comparison to Seachem's Ferrous Gluconate (Flourish Iron) supplement for aquatic plants.

[LabTest57]

Although there may be other possible ways to introduce plant fertilizers into the aqaurium, I'd rather go with Seachem's products, because in the end they use top quality ingredients. I can't say for sure that ferrous sulfate would work, but from the good comments I have read about Florish Iron I know ferrous gluconate would be the preferred choice; however, the economy will force some of us (consumers) to choose cheaper alternatives.

[Tech Support LK]

I have consulted with our Research Director on this and this was his reply:

Carbonyl iron (iron pentacarbonyl) cannot be used. It is not soluble in water. It is the form of iron that is used in magnetic tape.

I see no reason why ferrous bis-glycinate cannot be used. It is soluble, even up to a pH approaching neutral, and seems to be bioavailable.

Ferrous sulfate of course can be used. It, too, is bioavailable, but unlike the bis-glycinate or the gluconate, it is not "protected" meaning it can be readily oxidized to the ferric state. The plant can use the ferric iron, but only after the plant "treats" it with iron reductase, a material extruded through the plant roots. This places an energy requirement on the plant (plants have to produce the iron reductase and go through the process of reducing the iron), but generally plants can handle it. The beauty of the ferrous gluconate is that this extra work by the plant is not required.

Hopefully, this will answer your questions :)

[Tech Support GL]

There are a few differences between the bis-glycinate and the gluconate form. The number of carbons on each compound is different (gluconate has more carbons), the bis-glycinate contains an amine group, and the structure of the molecule once iron is bound will be different.

Bis-Glycinate coupled with iron maintains a stable ferrous iron structure. This structure keeps the iron from being oxidized. The previous explanation of the ferrous sulfate and bis-glycinate explains this, but I am guessing from this you would like to know which is more available to the plant? By all appearances, the bis-glycinate seems the better option in overall stability and absorption.

Dose accordingly, neither form will harm the fish (meaning maintain a very low level of iron in the tank similar to the suggested .1 mg/L for Flourish Iron).

[LabTest57]

Doesn't ferrous sulfate offer sulfates to the plants as an extra nutrient, too?

[Tech Support EH]

Technically, yes, but plants in general only require very low levels of sulfates. Therefore, we would not really consider this an added benefit of adding ferrous sulfate.

[Cardinals]

Despite the technical arguments, I have yet to see any scientific evidence that ferrous gluconate works faster and/or more completely than Iron-EDTA in the planted aquaria.
At recommended doses, Iron-EDTA is safe, extremely cheap and has been used extensively in the plant industry for decades.

[Tech Support LK]

Most research out there on iron uptake in plants is done for purposes of providing information for farming. Therefore, the majority of research is done on terrestrial plants and using iron-EDTA. Ferrous gluconate is not really a suitable form of iron for terrestrial plants so no one has used it to perform these studies. However, we do know that ferrous gluconate is more loosely bound than FeEDTA under aqueous conditions. If we know that the iron in ferrous gluconate is more loosely bound under aqueous conditions than the iron in FeEDTA, then it is only logical to infer that all other things being equal the compound that more readily releases its iron will be the one to impart a greater net increase in iron. Last year, we performed an internal study comparing growth rates using both of these forms of iron. We showed enhanced length growth and iron uptake using ferrous gluconate. The owner of our company presented the study at the Aquatic Gardeners Association Convention. If you are interested in seeing the presentation, here is a link to the AGA site where I think you can purchase the DVD.

http://www.aquatic-gardeners.org/convention.html

[Cardinals]

[QUOTE=Tech Support LK;6953] Last year, we performed an internal study comparing growth rates using both of these forms of iron. We showed enhanced length growth and iron uptake using ferrous gluconate. The owner of our company presented the study at the Aquatic Gardeners Association Convention. If you are interested in seeing the presentation, here is a link to the AGA site where I think you can purchase the DVD.

http://www.aquatic-gardeners.org/convention.html[/QUOTE]

I am interested in the 'proof' that this product is better than Fe-EDTA as claimed on Seachem's label. This is a very interesting topic. How about posting this research in the public arena?

[Tech Support LK]

I would imagine that is something he will work on in the future, but I'll put a bug in his ear.