I do it once – when I break down the tank – using 3/4" tubing and a "buckethead" shopvac.
The 3/4"+vac combo works anytime though, for anyone on a different maintenance plan! ;) Careful of the weight in that vac though if you happen to be removing a lot of sand!
Use your hand to make and break the seal between the vac hose and the 3/4" to control suction without messing with the on/off switch. (Not my trick...someone here on R2R!)
A nylon paint filter makes a nice way to separate the sand from the water and smaller detritus. (Again, mind the weight....sand is
slightly heavier than paint! ;)) This is especially good for keeping the bad stuff out of your drains when you empty the bucket....just pull the strainer with the big chunks out and dump the bucket without worrying about clogging your drains! (Sand in a drain is bad now and in the future.)