Gsp help!

Hello everyone, i have a huge GSP and i set it at the very top of my rock in my 29 gal biocube. I've notice that the skin (mat) which is usually purple turning a pale white color, i have a feel that this isn't good. Can someone plz tell me what's wrong? is it the radiation from the light? is it too high/close to the light? my water param is fine only high in CA. PLZ help i don't want this one to die on me... thanks all!

Also, i have 3 emerald crab and i see them pciking on the poor gsp, could this be a reason why my gsp is turning white?(stress)

Also, there's also brown stuff coming out the mouth? i don't know what it is but i need some help asap b 4 my second gsp dies....

 

Can you get a pic of it?

I don't know enough to answer your whole questions but I do know most polyps eat and poop from the mouths. It could be poop coming out!

 

Must be a Green Polyp week seems like every day for the last week I see a issue with theses very corals .. Are they opening on the entire mat ? of where its turning pale does it open up in that area or just stay closed ?

Take a tooth brush and lightly scrub it off a little the fact the crabs are hanging in that area just tells me they have located a good food source. And thats enough to not let it open . Change floes to flush it clean of all settling detritus