Three weeks ago I purchased a medium sized star polyp colony. It has been doing great until my last water change. I had purchased RO water from my LFS and a week later found that I had been given mixed salt water instead of fresh. In any case, I unknowingly had been topping off with saltwater and my salinity went high. I made a small water change to bring the salinity back down. Through all that the colony seemed fine. However, I made my normal water change on Sunday and since then the colony hasn't opened back up. Any ideas?