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Re: Ferrous Gluconate

> From: "Christopher Coleman" <christopher.coleman at worldnet_att.net>
> I received the following today from Seachem in response to my
> question  regarding ferrous gluconate,  which is used in their Flourish
> and Flourish Iron fertilizers.
> >Iron gives the best response. A third advantage to the gluconate is that it
> is a
> >reducing agent and so helps to keep the Fe+2 from being oxidized Fe+3 (the
> >product also contains other reducing agents to aid in this process as
> well). 

Interesting.  Looks like I still have a bit of chemistry intuition left
after all these years...

So ferrous gluconate may join the list of cheap substitutes for expensive
aquarium chemicals.  Considering that one 300mg tablet, costing about three
cents, with about 35mg of elemental iron, will dissolve in 350 l (about 100
gallons) to give 0.1ppm iron, it looks like a big win even if you have to use
a higher dose to compensate for oxidation.  If you want to add some additional
reducing agents, I recommend vitamin C.

> >It is
> >also my understanding that EDTA iron is actually in the +3 oxidation state.
> >Greg Morin

Not mine.  Why bother with EDTA if you've got ferric iron?  I'm also a little
dubious about his implication that EDTA fools the customer into thinking he's
got a higher iron level than he "really" does, as compared to his product that
just oxidizes and precipitates as rust.

> As an aside, I recently inserted a potassium gluconate tablet consisting of
> 90mg
> equivelent potassium in the root zone of a giant hygro I suspected of having
> K
> defficiency. Actually,  there are two gian hygros with more or less the same
> level
> of symptom.  Only one of them got the supplement.  I'll post result if it is
> encouraging.

Good.  Report even if it isn't encouraging.  Btw, potassium is very soluble,
so both plants will likely benefit.  Let's have more reports of kitchen 
chemistry like this!