I have an established FOWLR tank that has 10 fish and numerous blue legged hermits and serpent stars all from the Florida Keys. I keep trying to add a few astria snails and they only live a day or two. Can't figure out what is causing just them to suffer???? I am setting up my larger tank very shortly in which I previously had a full reef system in which my snails actually tried to breed. Used to look like I spilled a gallon of milk in the tank every few months. Please help!