Are you sure its not Lobophora Variegata ..looks what i was battling a few years ago.Found some info on RC, they suggested a certain kind of tang,or sally lightfoot crabs.I went with the sallys,and within months,was totally gone.I know some don't trust any crabs.My fish are big,or a good size,still have a few sallys after the years.Zero problems,all they do is clean rock 24/7 here's an RC link
http://reefcentral.com/forums/showth...ight=lobophora