I had this Setosa colony for over 7 years now. 3 years ago, I trimmed the colony in half since I was moving and it was taking too much room. It's now about 10 inches by 6 inches. Last week it started to STN out of nowhere. My other acros and monti are all doing fine. In last ditch effort, I broke the colony off the rock and made frags and put the frags into my frag tank and a nano tank. All the frags also RTN overnight. Parameters are stable in the main tank. I even have frags from the same colony I made a month ago in my frag tank that are doing fine. In my research, Setosa are pretty hardy. Is there something particular they are sensitive to??