in my frag tank (a 55g) I have half of it dedicated to chiller, skimmer (well i have 4 and one is about 5 feet tall) calcium reactor, return pump, ph controller, heater, and some other stuff......and the other side is all frags (sps) with about a turn over rate of 40....i have a 1/2 inch sand (crushed coral) bed and live rock piled on top of it so not to much flow can get down there just enough to clean up the detrus and junk
Brad