Sand can be a little harder to clean than gravel. The way it is usually done is to hold the gravel vac a small distance from the sand so the flow at the sand is not enough to disturb the sand but is enough to remove the miscellaneous debris on the sand's surface. I have done it once so far in a new setup with fine sand. The sand I had before that was coarse enough that a gravel vac could be used almost like it was gravel.