[carym]

Iodine is important for creatures that molt (Shrimp and Crabs), if you want to dose it make sure you test or know when to add it; but normal water changes should be enough. The other item that I believe uses a lot of iodine would be Xenia, can't say for sure because it never grows in my tank (until lately; different variety) but if you don't have anything that requires it and it doesn't sound like you do your normal water changes should be enough.