Lugal's and Hydrogen Peroxide dangerous mixture?

ReefsandGeeks

New member
To give a bit of background, I am certainly no chemist so I'm just going off of what I heard from an experienced chemist on a non-reef related subject (Karl-Fischer Titration) that peaked my interest as a possible interaction between commonly used chemicals in our tanks.

During a seminar on Karl-Fisher titration, one reaction that caught my attention was that adding hydrogen peroxide to iodide can alter it and turn it into iodine. Now, piecing together random bits of chem info I've heard, in a reef aquarium Iodide is the less toxic form of iodine with iodine being more toxic. One fairly commonly dosed supplement is lugals solution, which largely contains iodide, with some iodine in it as well. Another chemical commonly added to reef tanks to combat algae is hydrogen peroxide.

Is it reasonable to say that if a reefer happens to dose Lugal's solution, that they should avoid use of hydrogen peroxide as this could convert the iodide in the lugal's to a more dangerous iodine form?

I've never heard this warning before, but I have dosed both of these substances in my tank at one point or another, but never at the same time. Can someone with some solid chemistry background confirm this so if it is a concern the word can be spread?
 
Generally, the amount of hydrogen peroxide people add to their tank is very small, and so I don't think there'd be much of a problem. The Lugol's solution itself probably is more of an issue than the conversion of iodide to iodine, in my estimation.
 
The oxidation of iodide (I-) to iodine (I2) by hydrogen peroxide certainly occurs under acidic conditions, which I think is what your friend was talking about with the KF titration. Since the reef pH is pretty basic, I think that you don't need to worry about a reaction between the H2O2 and I-.

I hope that helped (p.s. I am a chemist)
 
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