So I've had it in my tank for roughly 3 weeks, completely fine and healthy till about a week ago, closed up and retracted all the tentacles. I tried moving it to more flow, less flow more light, less light. High in the tank, low in the tank and in between. When's a good time to surrender on it and pull it out? All the rest of my corals thriving. It wasn't stung by anything else. And my fussy elegance coral and hammer coral are both doing fine and thriving one with pom pom xenia, zoas,shrooms and a few others. So I'm thinking it's not related to water quality. I've done a water change and changed the tank filter floss, both difference. Any advice from you experienced guys?