I have live sand in one of my tanks and vacuum it occasionally. I still use the siphon tubes that diffuse the siphon a little bit. I siphon into a bucket and then dump the water down the drain when doing changes. This way I can reclaim any sand that finds its way into the bucket and put it back in the tank. However, some people prefer not to siphon live sand beds much to allow microfauna to proliferate, using snails, stars and fish to stir the sand bed. Good Luck.