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The same way as gravel... at least for PFS... Some finer sands you have to wiggle your nose, hold one arm up, and squint just right or you'll suck it all up.
If it's PFS you do it just like gravel. I can shove my vac tube all the way down, and as long as I don't hold it down there it doesn't suck up any sand. Play sand or some of the other fine sands are almost impossible to vacuum.