If you have a lot of sand the best way I've found is to just put it in to a "builders tub" or one of those tiny solid plastic paddling pools, on a slight incline, then we use the garden hose while we rotate the sand. The dirty water flows away but the sand stays due to the weight. We just keep rotating the sand and running the water through it and it comes up nice and clean. After we pop it back in to the tank with some water treatment.
For general maintenance we use a "gravel vac" to help remove debris from the top of the sand.
