Patrick - I was noticing the same thing, polyps not extending that used to. checked all my params, everything seemed fine and I was mystified til last night when I saw a nasty ugly hairy crab in the middle of an acro colony calmly pulling out polyps and eating them one by one! The thing is a good 1 1/2-2" wide with big claws and I haven't been able to catch him. He's having nothing to do with glass jars baited with scallop. I tried attaching some scallop to a bamboo skewer and he does come out and pick at it, but won't come far enough out of the colony to grab him. Tried skewering him (yugh) but he's too fast and tough shelled. So, I'm in a battle of wits with a crab - and the crab is winning. Very humbling.