Just add a small amount of peroxide to a dip with water from your tank in a separate container. Add peroxide slowly until you just see it starting to "bubble" around the rock and polyps. Soak for 10 minutes, use a turkey baster to squirt water at the polyps. Rinse in another container of tank water and return to the tank in an area of good flow. This can be done up to 3 days in a row and placed in an area of high flow and see how it does. I lost a few polyps that were beyond saving, but I also saved some RPE's that were goners for sure. They are growing great now. All in all I've done this about 4 times and haven't lost a colony or frag I have done this to. If you are worried about peroxide, you can do a dip with Furan 2 and tank water. Search this thread for zoa fungus and Furan-2 dip. The person who did this took a lot of pictures and gave step by step instructions. I have also used this method with great results. IMO zoas shipped in colder months are more prone to getting fungus. Good luck!