Sand Cleaning?

What's the best way to clean pool sand from the bottom of my tank? I tried a gravel vac and didn't have enough suction to suck up the waste. The sand didn't get sucked up either. I then tried a tube and that sucked alot of sand up.

ive always used a gravel vac... just hovered over the waste and it seemed to get rid of all the nasty stuff.... then once in awhile I would kinda stir the sand a little with the end of the vac... I never dug it in like you would with gravel.