Hi Sephoraz!
It's an odd question as large amounts of sand are not usually sold by weight but by cubic yard-3'x3'x3'. You buy a "yard" or two "yards" or 5 "yards".
Depending on the surface underneath, you'll want at least 3" of sand, if not more, and you'll want it to cover at least a 16'x16' area so it's bigger than the pool. That would take about 2 1/2 yards of sand, minimum, so you'd get 3 yards. I have no idea how much a yard weighs and, of course, that depends in large part how dry it is. Intex used to sell a 16x16 vinyl ground "cloth" you put over the sand and then set the pool on. This helped protect the bottom of the pool. I would then put a blue tarp over the sand base in the winter and stake it down to protect the sand.