i use to have this type of prob ,, ,,i now have turned around this prob with better pump ,im using pan world 1100 and a 40 gal refuge on a 90 gal tank ,,,,and more clean up crew in my tank ,,tank is crystal clear ,and everything is on zero ,
seems like more flow of water helped as well as the clean up crew ...i agree with both marrone and jackson,,both have good points and both of those pionts worked for me ,,i have 100 hermit crabs and 100 snails ,,they do a great job clean everything ,,,most of the snail i have are sand sifting so the sand gets moved as well ,,