What brand of salt are you using? RO/DI? Have you checked for parasites? What temp? Do you have clown gobies or hitchhiker crabs that eat corals? Hairy crabs inside the coral will be troublesome. Acro crabs are not hairy. Do you have little white 3 to 5 legged starfish? All these and some big mouth blennies like the bicolor can agitate corals. So can trash in the water and fine bubbles. Some things are toxic such as carnation corals, some fish sold as basses and box fish family members. Check for polyp extension at night. If none on any ever show, Its time to evaluate chemistry and color temp of the bulbs. Did you buy the bulbs new or are they used from Ebay? Spent bulbs are not your friend. It takes a lot of information to answer such a question and even then, perhaps there is no absolute answer.