A python vac hose has a ball valve on it,I just choke down the flow a bit if its sucking up the sand.
I have pool filter sand,moon sand,aragonite and colorquartz in various tanks,and the gravel is rapidly disappearing.
The only problem that i encountered with sand is when my tank sprung a leak. And so i have to remove every bits and pieces of sand in the tank. Took me 3 1/2 hours to finish it.
i think you need to have good water flow with sand. that way all waste is blown towards the filter intake. added a powerhead and my sand looks great for over a week. this is pool filter sand btw.
I put sand in my tank but had to leave a layer of fine gravel bc the sand was too fine by itself. It does get dirty quick but its so perty. =) And plants grow perfectly fine in the sand..