I had read that CoralRX is all natural ingredients that were designed to be less harsh than straight iodine. Lots of posts on ReefCentral about how Coral RX is great, kinda expensive but no where near as harsh. Ive dipped everything in it, and some corals even have stayed open for the whole 5 minute dip and every coral opens immediattely after. It does kill everything though, and almost immediately.