EDTA? DTPA? Which is a better choice for Fe?

[Bryn]

Any chemists on here that could make a suggestion on the better choice for a Macro tank, and efficient up take of Fe?

Thanks

[KrazieKiKi]

I would be interested as well. Right now I'm just doing every other day dosing of iodide for my dragons breathe. Maybe it's a stupid question - what's EDTA and DTPA?


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[Michael Hoaster]

I'm hedging my bets and alternae using both!

The ferrous version (Flourish) claims that plants can more easily uptake iron in this state, which sounds good to me. This version does however, cloud my water for awhile.

I've had good results with ferric versions as well, with no clouding. Plus it has added manganese. I can't see a difference in my setup, so unfortunately I don't have a definitive answer. In theory, the ferrous version should be better.

[jraker]

Hey Michael, what did you use for ferric iron? I am thinking of experimenting with the ferrous and ferric versions.

[Mr. Wiggles]

Have you read through the write up my RHF?

http://www.advancedaquarist.com/2002/8/chemistry

I think that whatever you choose should be chelated with something (citrate or EDTA) to prevent precipitation. I'm a chemist, not a biologist so I can't say which would be best for uptake into plant cells. if you look at the Pourbaix diagram of Iron you see that at our reef pH of 8 and let's say an ORP of like 0.3 mV puts you in the Fe2O3 area so most would be as iron 3+. I think that whether you start with ferric or ferrous you will end up with mostly iron 3+ in the end and maybe some 2+ in areas with a locally reducing environment. Some of this may also be changed by the addition of the chelate to the iron solution, but it is a simple approximation.

As always becareful with this stuff, it could be easy to overdose and grow a lot of cyano or hair algae if you don't have the dose matched with the consumption.

I hope some of that made sense.