What’s Eating My Iron?

[Dan_P]

I wanted to speed up nitrate reduction in my fish only system. Dosing iron was one option and if my system was iron limited, I might see an uptick in nitrate reduction. I did not see an uptick, but the iron (Seachem Flourish iron (II) gluconate) seemed to disappear too quickly. I did three experiments to shed some light on whether the disappearance was biotic or abiotic (see the table below).

The first question I wanted to answer concerned the chemical stability of the chelated iron. The first experiment, “time expt”, answered that question. Iron gluconate is stable in seawater. Next question, did GAC remove the chelate. The answer was “yes”. Stirring freshly prepared saltwater spiked with with iron gluconate with GAC results in a rapid decline in iron. How about the impact of the skimmer? Yes, it too was removing iron, likely the gluconate chelate, from the system.

Conclusion. Since iron might be sufficient in nanomolar concentrations, dosing 0.2 ppm Fe probably exposes the systems organisms to this level or above for only a few days.

 

[monkeyCmonkeyDo]

What? LOL

Dude, this is way too much chemistry. Yes, theres chemistry involved but its mostly biology bro. lol.

Why are u dosing iron in a FOWLR tank? Get a better filter....bigger filter....more water volume....less fish.... idk something. Iron imo would only need to be dosed in a high demand coral tank....why are u looking at iron even in fowlr?
?
-d

 

[BeejReef]

That's interesting, particularly with the increasing popularity of chaeto fuges.

Simple (very simple by comparison) question for you. I dropped one finishing nail, maybe 3/4" long, made of galvanized steal into my tank and lost it into the sand.
I know this is not "good," but, should I be overly concerned, or will my GAC and chaeto simply eat it up as it oxidizes? Weighing the possible harm of the nail versus the stability swing of halfway emptying the tank and sifting all the sand ISO of tiny nail.

I had actually given some thought to researching allowing tiny bits of relatively pure iron to oxidize in the sump as a form of slow-release iron dosing, but this wasn't that.. Just fat fingers when adding trim to canopy.

 

[Skydvr]

If you have an idea where it went in the tank, use an algae scraper or something else with a strong magnet in it and see if you can get that nail out of there.

 

[BeejReef]

If you have an idea where it went in the tank, use an algae scraper or something else with a strong magnet in it and see if you can get that nail out of there.

"Magnet" = Genius!

Can't believe I didn't think of that. Ty

 

[Skydvr]

Ha!

Sometimes you lose sight of the simple solutions trying to figure out if everything will be okay or if the tank is going to melt down.

Not sure what you have available for magnets, but use something that is fully imbedded in plastic if you can. A lot of magnets break down rapidly in seawater. Not sure how big of a deal it would be using a bare neodymium magnet in the tank for 5-10 minutes searching for the nail, but losing that in the rockwork would be worse than dropping a handful or two of those nails in the tank.

 

[taricha]

This is a cool result the bridges a lot of the gap between the very tiny (but crucial) actual biological requirement for iron and the massive Fe doses that are recommended and then depleted in fairly short (weeks) time frames.

 

[Dan_P]

This is a cool result the bridges a lot of the gap between the very tiny (but crucial) actual biological requirement for iron and the massive Fe doses that are recommended and then depleted in fairly short (weeks) time frames.

Thanks!