Very true. The benifits of iodine on corals are unsubstantiated. Some aquarists say it works and others see no benifit. Its main use for corals is in disease treatment. A LFS by me does Lugol'sdips on all of the new corals before adding them to the tanks.Iodine is also a supplement that some of the corals seem to need, like Xenia, Kenyan tree coral. But as JG says iodine levels are usually sufficient with proper water changes