One of my duncans has begun to stay in it's skeleton. It's got 6 heads and 3 now are really sunken while the other 3 aren't looking too good either. My other 2 headed one seems fine. I have recently moved them both as they were in a bit too much flow but the one head had already started to look sad. The only thing I have changed recently is adding carbon. All my other corals and fish are fine. I only have T8's but there are 8 altogether and the corals are about halfway down in medium flow. The last water test was ok apart from calcium and mag being a bit high but it's always like it. Has anyone any thoughts as to why the Duncan is like this? Could it be because of the carbon? It really did well for the 1st 2 months in my tank so I'm baffled.