I have a 65 FOWLR tank (only about 26 pds of LR) live sand also. I just added a second red-legged hermit crab and thinking of taking him back out. I am worry with two of them, they may be eating too much stuff. They are both good size, about an inch. I do have extra shells in the tank, but not really big. Thanks. I think it is ok, but want to hear what other think about it.