I have a tongue coral that has been receeding for a month now. Every other coral is fine including the baby next to it. I see hermit crabs and snails on it pretty often. I feed him a few times a week, have dipped him in both seachem reef dip and coral rx. He lives in the middle of my sandbed in 90 gallon with 2 150w mh. Anybody have any ideas of how to get him back to health? Today I fed him in a small container and made sure he closed the food in before returning him to the tank. Could it be the crabs or snails?