I got a nice yellow leather coral about a week ago. It looked nice for two days then it started getting a dark brown slime film on it. The coral is now more of a yellowish green in color. The film occasionally blows off with the current. The polyp haven't came out since I put it in my tank. All my other corals are doing fine and my levels are good. I have 175 watts MH and 150 of VHO actinic. I have moved it from the bottom of the tank to the top and it didn't really make a difference. Is this a normal adjustment for yellow leathers or is this abnormal. The place I bought it said they were very hearty but some times took awhile to adjust to a new tank. Is this true? Thanks for any advice.