Hi Steve, if you can remove the coral a hydrogen peroxide dip would help. 1 parts hydrogen peroxide to 3 parts tank water for a minute or two should help. If they are in the tank turning of the pumps and using a turkey baster with just the peroxide for a minute or two should do it.
For sick zoa's I usually do revive dip, if that doesn't work I'll try Iodine dip. If all else fails Furan-2 dip usually works for me. Never tried the hydrogen peroxide dip I thought it was for algae treatment only, I'll have to try that next time.
