Lugol's or Iodine Dip... Lugol's is a concentrated iodine solution, 40 drops to a gallon of saltwater for no more than 7 minutes, should effectively disinfect a coral. Do NOT use this procedure on fish, although I've used it on Sea Stars with some good results. Do NOT dump the dip water back into the tank, discard it. If you're using something like Kent Tech - D or Seachem Reef Dip, follow the directions on the package. Those products use Iodine and Potassium Bromide and other compounds to achieve the same end - to disinfect corals of bacteria and other pathogens.
From JennM on the reef tank.
I have used this several times with no ill affects on my corals, keep a close eye on your corals as some tend to not like this.