You do not clean sand like you do gravel. Stuff falls down between the grains of the gravel and rots there, that is why you tend to dig deep with your gravel cleaner. Sand is much finer. As long as you clean regulaly, the particles of crud tend to sit on the surface of the sand and can be sucked up as Wolf said.
It is important to keep your sand open though. Poke and prod it around from time to time. I use a chop stick. This stops it packing down to hard, and can also prevent undesirable anærobic bacteria build ups. How often and how much depends on the sand. Even grain size and shape like swimming pool filter sand doesn't need a lot of "gardening", silver sand or building sand requires more.
