# How long can Iron last



## john.shephard26 (Mar 8, 2011)

Hi, I was wondering, how long can Iron last diluted in water and under assumption that is kept in a dark place and good container?


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## Bert H (Mar 2, 2004)

I keep the bottles of Flourish iron as long as they last me. These are chelated solutions and, it is my understanding, that will last a long time with no problems.


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## john.shephard26 (Mar 8, 2011)

My solution is all most a year old and since I've made it, it got a little bit darker should I be worried?


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## Bert H (Mar 2, 2004)

Sounds like a little oxidation occurred, I see the same thing with mine. I wound keep using it.


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## john.shephard26 (Mar 8, 2011)

Well I don't really have a choice, If I overdose a bit with Iron what should I expect?


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## Zapins (Jul 28, 2004)

john.shephard26 said:


> Well I don't really have a choice, If I overdose a bit with Iron what should I expect?


...darker colored water of course!

Plants like the +2 form of Fe, which is lost when iron rusts to the +3 form. The +3 form is not as available to plants and I believe they have to do some extra chemical manipulation in order to use it, though the vast majority of plants can't do this chemical process which basically means its useless. So, overdosing is a good idea to increase the chances of getting any usable Fe left in the solution to them.


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## john.shephard26 (Mar 8, 2011)

Daaam!!!I guess I have to rely on CSM+B.


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## OTPT (Sep 27, 2010)

Zapins said:


> ...darker colored water of course!
> 
> Plants like the +2 form of Fe, which is lost when iron rusts to the +3 form. The +3 form is not as available to plants and I believe they have to do some extra chemical manipulation in order to use it, though the vast majority of plants can't do this chemical process which basically means its useless. So, overdosing is a good idea to increase the chances of getting any usable Fe left in the solution to them.


Whoa whoa whoa. Fe3 is effective too. 
You said as if the majority of chelated irons are in Fe2.
But ALL EDTA irons are in Fe3 form as stated here and elsewhere. 
http://www.seachem.com/Products/product_pages/FlourishIron.html

If you refuse to use Fe3, there are few choices left.
I wonder if Fe(2)-DTPA exists, all DTPA irons I can find are Fe3.


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## Zapins (Jul 28, 2004)

My mistake, I was thinking about the gluconate Fe2 form when I wrote that. If a gluconated Fe2 solution turns a different color over time it has gone "bad." You are right, chelated iron is Fe3. However, plants still prefer Fe2 and will use it preferentially over Fe3. I think this is because Fe3 is usually found as iron oxide in nature (rust) and rust really doesn't dissolve in water very well. Interestingly one of the uses for Fe2 is as Fe2-sulfur - used in the oxidation-reduction reactions of mitochondrial electron transport chain to make energy.

So over time plants have just adapted to using the Fe2 preferentially since it is more available. I think that is why they chelate Fe3 - so it becomes more soluble in water and therefore more available for plants to uptake. But then you still have the problem of getting the Fe3 out of the EDTA and then converting it to an organic bound molecule for use in metabolism. Yes it happens, but Fe2 gluconate already solves all of these problems, sort of like how plants like ammonia over nitrate and nitrate.

CSM+B can also go bad over time by the way. More then just iron can become useless if the CSM+B is very old (years).


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## john.shephard26 (Mar 8, 2011)

So its safe to use this solution that I have...thats nice...What happens if I overdose a bit?
And about CSM+B ...do you mean in its dry form or solution...I dose it (and keep it) in a dry form.


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## Zapins (Jul 28, 2004)

If you overdose a bit I doubt much would happen, but it depends on how much iron is left in chelated form, if 99% is still as it was when the solution was fresh then.... you are overdosing, if 25% left then maybe under dosing. I suppose if you have been dosing iron over the last few weeks and have not had any iron deficiency symptoms then keep dosing as you have been, why change if it is working right?

CSM+B will not last forever in dry or liquid form. It is exposed to oxygen and water - both chemicals that promote rusting of many of the micro nutrients. I'm not sure what the shelf life of CSM+B is but I would guess it isn't too nutritious after 1-2 years.


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