As I recall, an iodine test kit will not give results for all iodine ionic species: iodine, iodide, & iodate. These are oxidizers and rapidly shift from the strongest (iodine) to weakest (iodate) ionic species.

I believe iodine changes to iodic acid when dissolved in water. I have heard different things about which species are bio-available and which aren't. Maybe some online research would be worthwhile here.

Here we go:

http://www.advancedaquarist.com/issues/mar2003/chem.htm

Gary