That's a good question. My water movement is such that detritus settles in only 3 locations and all the rest of the sand remains very clean. I siphon these 3 areas off before water changes as part of regular tank maintenance. Amcarrig is right when she said that CC shouldn't present a problem if it's cleaned regularly. To me, it's just another variable to add. Why have a bottom that needs to be scooped up, disturbed and vacuumed? Been there and done that. THAT'S where that big dustbowl to which you refer is created. In a tank with a sand bottom, so long as there's ample water movement, the sand remains clean.