You won't want to do this in your tank. My suggestion is to remove the rock with the polyps on it and try to cut out any healthy remaining polyps and put them on several frags, then dip these each day in the furan II. If your local fish store doesn't carry furan II, then just do a google for it. You can buy it in 10 tab packs, or big 1-2lb jars (spendy). A 10 pack should do the trick in your case.