I have sand and use a python... i stir up the sand (required to avoid bacterial contamination) and i vacuum the top layer with my python, like i would with gravel. the sand will fill the vacuum end of the python, but most of it will fall back down.. you will however manage to suck a few tablespoons of sand out of the tank (depending on the size/quantity).... in my bigger tanks (90+ gallons), the amount of sand that makes it out is larger, but i just vacuum it right out the door into my garden.. .. you can vacuum it into a bucket and save what's there to put back into the tank.. but IMO it's not woryth it, and i've only had to "top up" or replace the sand once in the last 2 years, and that was only for my 10 gallon tank.. i've never added to any of the other ones.....
hth...
decz