[BoomerD]

If you do regular 10% or more water changes, your salt mix should provide all the iodine your xenia will ever need. As has been mentioned above, Iodine is very tough to measure, and the line between "just enough" and deadly toxic" is VERY fine...Most supplements tell you to add "xyz number of drops per gallon every day. Unless your tank has a high iodine load, the addition of the supplement daily could easily and quickly push your tank over that line. Another mis-conception about iodine is that it is needed to help shrimps molt. In actuality, too much iodine forces them to molt to get rid of the too-high levels in their systems.
Just do weekly 10% or more water changes, and you shouldn't have to supplement anything except perhaps calcium and alkalinity buffers, and again, ONLY when you test to be sure what your tank levels are, so you can know how much the tank needs.