+1 on a 15-20 min Iodine bath...
I prefer not doing freshwater dips on my corals because of their poor ability to osmoregulate, I fear that some polyps may get damaged (cell repture) duing the procedure. I do however dip all my new corals in an iodine bath like Tropic Marin Pro Coral Cure before introducing them into my tank. Understandably I get a bit paranoid about introducing things like flatworms into my display tanks. Besides preventing flatworms, I also believe that dipping a new coral in an iodine solution helps it recover from the stress of transport and reduces the chance of microbial/bacterial infection on the new coral.