I have a 1 head frag that has stopped extending fully. It is coloring up from the paler brown to a more green color, but one side is tightly closed, while the other is about half extended. Nothing is close to sting it, and everything in the tank is extending normally. Porites, purple tip acro, turbinaria, caulestra, acans, euphellia,blasto's and zoos are all doing great. The duncan is in moderate flow, and about 20" below a 250 halide with 130w pc actinics. Is it normal for them to go into a period of non-extension like zoo's? Do they do this when they are about to split polyps? I also feed the tank cyclopeze daily.