I bought a emerald Crab to work on my bubble algae but in its first day in the tank it has been nothing but trouble. It knocked two coral frag off of the super glue. Then last night i came out to check the tank after dark and the damn thing looked to be picking at my coral!!!!! Should I pull this thing or am I misinterpreting what it is doing? Of course the LFS said "it was a 100% reef safe"