When I do waterchanges, I vacuum the sand bed. I do this once a week when I change the water. I dig down about an inch deep in all the sand I can get to easily. I guessing my sand bed is about 2" deep in places. This keeps all the detruis at bay. I know theres some people that would consider this dangerous, but I've never had any adverse reproccussions from doing it.
This IS NOT a recomendation that you do it........ Only telling you what I do and the results I get.