If you're talking about star polyps then I've heard they like medium flow. I keep mine in the middle of my tank with med. flow and they seem to be doing great. I've noticed some growth and they are always open(during the day).
Dittp to strikers answer..I keep mine, middle to middle high in the tank, and med water flow, and they are doing fine,,EXCEPT FOR THE DAMN HERMIT CRABS EATING THEM!!!!!(but they are OUT of the tank tomorrow!!!)
~Susie
they favor best in areas of medium to high current ..in nature they thrive in areas of stronger current and grow into huge mats ..as the flow hits them they flow like reeds of grass it's quite beautiful.. anyway.. put them in good current...
Brian