Why Dose Iodine or Iron?

Brent Bohannon · Sep 2, 2021

After reviewing my ICP results, it shows that I have 0 iodine and 0 iron. I am dosing 3.5 ml/week of Red Sea Color A and C based on my calcium consumption. I wanted to raise the iodine to 50 ppb, which puts it in the middle of the spectrum recommended by Triton. I read the directions on Color A and it says 1ml will raise 100 L .03 ppm. How is this even manageable? That means for my Red Sea 250, I would need to dose 5 ml to achieve 60 ppb of iodine from a starting point of 0. The problem is the same for Iron. If the margins are that slim, why are they not packaging the products at a lower molarity (concentration). The potassium color only raises it 1.75 ppm and the amount needed in a mixed reef is much higher according to Triton. I'm having to add 170 ml to get my levels up just to the midpoint. I feel something is a miss. Either the ICP test is not accurate with regards to iodine and iron or they just don't need to be supplemented at those levels or at all. For reference, I have been auto dosing the colors for at least a month prior to the test and intermittent dosing for a while before that. If I am wrong please set me straight.

vetteguy53081 · Sep 2, 2021

Iron good for chaeto … Xenia and macroalgae
Iodine for zoa, euphyllia and Lino type coral

Randy Holmes-Farley · Sep 2, 2021

IMO, iodine may not be useful, but it is easy to experiment and see if it does anything useful in your system.

Iron is definitely useful, and some folks who have dosed it see an almost immediate change in macroalgae. The owner of ReefCentral saw his macroalgae turn green almost overnight when I suggested he dose it. That said, iron does not need to be detectable by ICP to be plenty.

My Triton Testing Results: By Randy Holmes-Farley - REEFEDITION

Recently, Triton GmbH in Germany has initiated a method of testing many ions at once for a single price. In the US, that service is coordinated by Unique Corals. For $49 they will send you a couple of tubes to collect a tank water sample, and a prepaid mailer to send the sample back to them...

www.reefedition.com

Iron (Fe). The natural iron level varies a lot with depth, but surface seawater may have only 0.006 µg/L. The Triton LOD = 0.3 µg/L. I dose iron, and when I dose it I boost iron to roughly 1-2 µg/L, which would be detectable. This sample was taken more than a week after the last iron dosing, and none was detected as it gets depleted in the meanwhile. I’ve not yet seen a Triton test result for a real aquarium sample that had detectable iron, but that doesn’t mean these tanks are necessarily deficient. Iron is also a case where the form is critical, and ICP cannot distinguish form. Binding to organic matter, for example, can alter the bioavailability of iron.

Paul B · Sep 2, 2021

Dosing Iron.

Brent Bohannon · Sep 2, 2021

Thank you Randy. That answers my question. I am not a fan of dosing something that has such a small margin of error due to the concentration of the dosing solution. I think I will just leave the dosing as is and not worry about what the ICP says.

Stephers · Sep 2, 2021

Here's my anecdote about iodine. I have a plating monti that, like clockwork, would start to fade and bleach on the edges about 5-6 days post water change. So I'd do another water change and it would immediately perk back up, only to start fading again 5-6 days later. This had gone on for months and months to maybe over a year? I just got into the habit of doing a weekly water change to save it. I even made a post about it on here. Couldn't figure it out.

My last ICP said I had zero iodine and so I did the suggested dosage and immediately my monti perked back up as if I did a water change. I continue to dose iodine at a maintenance every 3 days and the monti looks better and better. It's almost been 4 weeks now. I have other plating montis in the tank that didn't have this problem and no other corals seemed to benefit so dramatically (although I did notice improved colors on some). I read other people specifically claiming their montis having problems from lack of iodine too. I suppose the water change was just enough to boost iodine until they fell to zero again. So take that for what you will!

Righteous · Sep 3, 2021

I can confirm iron dosing effecting macroalgae. Without iron dosing, my Chaetomorpha usually had pale sections. In addition some Caulerpa I added had almost died off completely. With iron dosing the Caulerpa has taken off, and the Chaeto is always dark green throughout.