There is enough flow in the tank that the filter catches most of it. I have an eheim 2217 and a eheim 2028, plus a power head on the tank. I don't even vac my tank because the sand is rarely dirty, also I can't reach the bottom XD.
Every once in a while I take all the rocks out, usually to catch a fish, That stirs up some stuff so I do a large water change afterwards.