Sand is not idea for bedding pools, unless you are on dead level ground, with no way for the sand to move.

Limestone sand is much better, if that's available in your area, but even that can't be used if there's a possibility of a current washing it away.

Also, many folks use dug-in pavers under the poles.

Good luck.

PS. Read the SSR, and make SURE you are ready to start that, the minute water enters the pool. If your water is of questionable quality, it's especially important to get the Unicel cartridges.