Long tentacle plate coral

[tweetysox]

im running 2x65w pc lighting, no fish have been swimming near it i only have a clownfish and a velvet damsel in my tank. it just closed up one day and never opened. Christy says i should run carbon but for how long im new to this great hobby and have had no problems till now. If it was chemical warfare wouldnt it affect my hammer coral, brain coral, candycane or my umbrella mushroom corals? Do you all think it may be dying??