i purchased a large frag of brown acropora about a mont ago from a frag trade show....i brought it home and it began to darken up and polyps were nice and o0pen for about 2 weeks ,then i noticied that the polyps had stoped opening....and last night i notices some "bleached spots" i look at it today and it looks as if the brown "skin" is falling/peeling off revealing a white skelton.......what could this be,i thought maby not enough light ,its under a 186w pc....about 2 inches under the waters surface..any idea of what this could be thx