chemistry question..

[Tristan]

mostly for DEA but for anyone else who knows...
if Fe and other stuff in the water get oxidised....
like Fe2+ into Fe3+... can we reduce it back to Fe2+ with..er.. antichlorine? it's sodium thiosulphate rite? thanks...
also.. is EDTA Fe all in Fe3+ form? thanks...

[UnderWaterWorld]

Anyway EDTA is just a molecule (technically called a ligand) that can bind to metal ions (via coordinate bonds). EDTA can both chelate iron(II) and iron(III). Adding thiosulphate (a reducing agent) will reduce iron(III) ions but the problem is, your tank is so big, with so many other chemical species in the water, so adding this reagent reduces whatever it can reduce, not specifically iron(III). Besides the conc of thiosulphate in antichlorine is not that high, to reduce all the iron(III) to iron(II), Im afraid you need gallons of it. Correct me, if Im wrong.

[DEA]

in theory yes
but leave well enough alone
you never know what other things will happen
much safer to use other methods like redosing on a regular basis
some anaerobic bacteria are supposed to do that too

according to greg morin from seachem
edta chelated iron is in the fe3+ state
possible in the 2+ state, but simply doesn't happen
i would suppose it's got something to do with stability
wilson u wanna add on pls do

if you check the APD archives you'll find one big hooha regarding iron gluconate and iron edta

[UnderWaterWorld]

I would also recommend redosing instead of reduction of iron(III) ions. Anyway chelation of some metal ions by ligand (eg. EDTA) makes them more resistant to reduction, if I am not wrong. In any case, your iron ions in the tank should not be in the EDTA form, unless u added the reagent. Make life easier, get yourself a bottle of appropricate solution, rather than trying out something risky. Not trying to discourage one from being innovative, but we all lack the laboratory facilities to check if our theories are right or not, not to mention, we are also at the same time, risking our prized tank inhabitants... []

[Tristan]

ok... thanks guys...
so it won't work rite? ok lah..
i'll just keep adding fert.....
anaerobic bacteria reduce iron? hmm... ok.. i think my substrate is getting a little anaerobic...

[UnderWaterWorld]

Tristan: Its not that its not gonna work. Im sure it works, just that we do not know what happens besides that reduction u wanted. It is because the aquarium, albeit simple, is a very complicated system on its own. When you add thiosulphate, it reduces anything that it can reduce, and it might reduce things that u dun want and could be harmful to your fishes... Anyway dosing with iron is really much SAFER and cheaper too...

[Tristan]

rite.. got it UWW

[DEA]

^ ^
eh wilson, you say exactly what i wanted to say but didn't go into cos i thot was too cheem