Carbon and Iodine

[gibbs.david]

I’ve been struggling with Zoas and one suggestion was Iodine depletion. Thinking about when the problems started I did change my carbon source. Is it possible that this carbon is depleting trace elements including Iodine ?

 

[Cory]

Yes activated carbon removes iodine. Not sure about trace elements though. If they are bound to an organic then yes carbon can remove trace metals iirc.

 

[Randy Holmes-Farley Verified Community Expert]

Actually, I am not convinced GAC removes significant iodide or iodate from seawater and have never seen any data to show it does (I'd love to see such data if it is available). Carbon aside, iodide is rapidly depleted from many/most reef tanks as it is taken up, especially by algae of various types but also by other organisms. This happens without GAC around.

I'm not convinced that supplemental iodine is needed by zoanthids, but it is an easy experiment for reefers to test for themselves.

My suggestion is if you are thinking it might be an issue, to dose iodide and see if it benefits your tank. :)

 

[Cory]

I tried to find something about gac and iodide for you, but found this, true?

When iodine ends up in surface waters, it may escape as iodine gas.

Read more: https://www.lenntech.com/periodic/water/iodine/iodine-and-water.htm#ixzz56XEEmUw7

 

[Randy Holmes-Farley Verified Community Expert]

They are certainly correct thsat algae takes up a lot of iodine. We don't have appreciable I2 in seawater. It is I- and IO3-, which do not go into the gas phase. :)

 

[Cory]

They are certainly correct thsat algae takes up a lot of iodine. We don't have appreciable I2 in seawater. It is I- and IO3-, which do not go into the gas phase. :)

I cant remeber if ozone usage would convert it to I2. I wonder if ozone could cause iodine to escape.

 

[Randy Holmes-Farley Verified Community Expert]

I cant remeber if ozone usage would convert it to I2. I wonder if ozone could cause iodine to escape.

Makes IO- and IO3- from I-.

I discuss it here:

http://reefkeeping.com/issues/2006-03/rhf/index.php

 

[Joe Batt]

(shows iodine removal from water with gac)

Should we run carbon just briefly once or twice a week to remove the yellowing and nasties from the water so as not to reduce iodine, or would we be better running ozone so as not to deplete iodine?

 

[Randy Holmes-Farley Verified Community Expert]

As I stated earlier in this thread, that binding is not pertinent to our situation. Yes, GAC is very well known to bind iodine as I2. There is a standard test of GAC surface area that involves seeing how much I2 can bind when nothing else is competing for binding sites (the Iodine Number). But we do not have the form I2 in seawater, and we have huge amounts of similarly looking ions (chloride, etc.) to compete for binding sites. The video is not looking at the forms we have in seawater

There's no evidence, and I think it unlikely, that GAC binds appreciable amounts of the forms of iodine we have (colorless iodide and iodate) from seawater. :)

 

[Joe Batt]

Thanks Randy. I currently run carbon 24/7, what are the thoughts on that? Is it too much? Does it strip too much from the water if run that much? (I change it weekly/bi weekly)

 

[Randy Holmes-Farley Verified Community Expert]

I currently run carbon 24/7, what are the thoughts on that? Is it too much? Does it strip too much from the water if run that much?

I always have. Whether it removes too much or too little of anything depends, presumably, on how much you use. :)