Potassium and Iodine?

WillB · Oct 29, 2018

Is there any real science behind the dosing of potassium and iodine? I’ve been curious about this for a while but have only been able to find anecdotal reasons for their dosing.

Oshengems · Oct 29, 2018

I can tell you that with Iodine I saw a difference in my corals they looked more vibrant I would say specially new growth,

Edit: SPS only specially Acropora with blue/purple/green

ReefTeacher · Oct 29, 2018

People get conflicting results. I definitely see that my leathers open more fully and my Fiji Yellow responds very well to iodide additions. But I watch with ICP to make sure I don't over dose. Others see no difference. I do occasionally dose potassium when my ICP says it is low, this happens once or twice a year. I do not note any particular change when I do, but it can's hurt to top up to seawater levels if it's dropping right?

Oshengems · Oct 29, 2018

Oh my Xenia’s look fuller also when I dose constantly

sghera64 · Oct 29, 2018

Are you asking about iodine or iodide?

Iodide is more straightforward, iodine can be a mixed species with different forms and effects.

ReefTeacher · Oct 29, 2018

Sghera4, I am not so sure. The only 2 common states of Iodine we would see in our tanks would be I2 (iodine) and I- (iodide) . Of course in the presence of ozone we would see higher states as well. But ultimately, the redox potential of you tank water is what it is, and the tiny fractions of a mole of either iodine or iodide that you add would probably reach equilibrium in your tank very quickly. (within minutes if not sooner) So it may not really matter if we add iodine or iodide; it will probably speciate the same way anyway.

sghera64 · Oct 29, 2018

ReefTeacher said:
Sghera4, I am not so sure. The only 2 common states of Iodine we would see in our tanks would be I2 (iodine) and I- (iodide) . Of course in the presence of ozone we would see higher states as well. But ultimately, the redox potential of you tank water is what it is, and the tiny fractions of a mole of either iodine or iodide that you add would probably reach equilibrium in your tank very quickly. (within minutes if not sooner) So it may not really matter if we add iodine or iodide; it will probably speciate the same way anyway.

I hear ya. I dose I2 with a pinch of KI (Logul’s). However, I think Randy H-F has convinced me that using I2 can lead to up to six different species of Iodine. I think he might be referring to the different oxidized forms of iodate.

Do you know anything about that? I’ve not researched it (yet).

WillB · Oct 30, 2018

sghera64 said:
Are you asking about iodine or iodide?

Iodide is more straightforward, iodine can be a mixed species with different forms and effects.

I haven’t dosed either before. But I guess I’m curious about both and what effects they have. Do you know how it is used in our tanks?

sghera64 · Oct 30, 2018

WillB said:
I haven’t dosed either before. But I guess I’m curious about both and what effects they have. Do you know how it is used in our tanks?

Randy Holmes-Farley is the expert on this and has a few articles out there that will help you. Here are some links:

https://www.advancedaquarist.com/2003/3/chemistry

https://www.advancedaquarist.com/2003/4/chemistry

ReefTeacher · Oct 30, 2018

So I reread the Randy Articles (I'm sure I had read them years ago) and I realize I was incorrect. It seems from MANY sources online that Iodate, IO3-, is the predominant species in the ocean, over iodide, I-. But I stand by my statement before, given that the concentration is in the neighborhood of 60 ppb, it probably doesn't matter which one you add, equilibrium will be quickly reached.