Quick help with brain coral needed

We have a green brain coral, (Trachyphyllia radiata) or very similar at work. We've had it for about 3 weeks in an established reef system. Our polyps, , mushroom, leather corals and sponge are big and beautiful but this guy has yet to open back up from what he was in the LFS. He has also begun to turn white around the edges. I thought it could be from bleaching but we've tried him high up near the lights and at the bottom. Water parameters all check out ok, as well as calcium. We feed plankton and dose with strontium and molybendenum from Kent. We hae a spotted mandarin, several clowns and yellow and a blue tang all happy. So I'm not sure it's anything in the water. I'm thinking it may be something that's NOT in the water, something we've overlooked in moving from polyps and mushrooms to our first LPS. Any ideas?

Oh yeah, Lights are power compact ~285 watts half 10,000K half blue actinic in a 75 gallon tank.

Yes

we run twin carbon pads on a 300 biowheel hang on filter to go along with our bio balls and live rock. We also have a protein skimmer.

carbon was changed a little over a month ago and the skimmer is skimming and producing scum.

It's been in about 3 or 4 weeks, we moved it today in hopes that the white color was because it was too close to the lights. We've tried him near the lights, on the bottom and in the middle and he has yet to expand like he was in the LFS. (like when they get happy) But today and yesterday we noticed the edges turning white. I don't have much experience with corals, (this is the work tank) and the only thing I've read here that sounded reasonable was bleaching. so we've moved him 3 times in a month and he has yet to be happy anywhere in the tank.

and nothing was touching him or messing with him. We also have 5 feather dusters of various colors and I thought those were supposed to be fragile but they are very happy. I can't let this brain coral kick our butts!