I'm on the same boat as mrg02d, only my situation was with live rock instead of the sand. Only the rocks were so nasty and dirty that most of the grime transferred to the sand, which made my sand disgusting. A nice clean sandbed is always best, and trust me, once grime, dirt, and decaying matter mixes in with the sand, it's almost impossible to get it all out and have the sand clean once again. I cleaned my sandbed EVERY day and still, day after day, junk always came out from the sandbed.