My zoas have not been doing good at all. Closed up for the past 2 weeks, so I kinda knew they were on the way out. This morning the rock that they were on is completely bare. I guess they all melted away last night, I see no trace of them in the tank. Will this hurt anything? Ive heard about zoa being toxic, what about putting my hand in the tank? Ive got some finger leather corals, and gsp they are all doing fine. Fish seem ok. Should I do a water change?