what i do once in a while.....take a long hose, connect 1 end to ur sump wool filter, the other end juz above ur fingers.....use ur finger to dip into the sand n stir, the dirt will be sucked into the hose in ur hand to the filter in the sump.....quite time consuming but the sand will be alot cleaner after that....i did that for my dsb n all LS is okie......but do at ur own risk....