[martinmcnally]

I found with a few colonies that when they do this take out a turkey baster and blast them to clean everything away. That sometimes works. Then look for the little worms that can sometimes popup around them. They look like little tubes and I see them come out at night and sting the zoas. Break those off if they are close by. Good idea to take a look at them during the night and see what is going on. Too much light is definitely another killer and it wont kill them right away might take a week or more before they start to close up.