There are a few different things that people put under their above ground pools. You can put sand, or you can put a tarp. If you put sand, you have to make sure that it is compacted so that the pool doesn't move. If you put a tarp, then you need to make sure that it is weighted down so that the wind doesn't blow it away.

There are a few different things you can put under an above-ground pool, but the most popular option is to put sand underneath it. This will help to stabilize and support the pool, and it will also help to protect the ground underneath from moisture damage. You can also put some type of paving material like concrete or bricks underneath the pool, or you can use a plastic liner to protect the ground.