Level the ground. If extreme enough, you end up with a half above and half in the ground. The other possibility is to have the pool of varying depths.
Backfilling around above ground pools is not necessary or recommended.
Disassemble the pool, grade the site, install pool
The purpose of an above-ground pool cover is to prevent leaves, dirt and other debris from falling into the pool reducing the frequency that the pool needs to be cleaned.
Chlorine level in an 18' above ground pool should be between 2 and 4.
Dissassemble the pool -level the landscape/ground - check site to make sure it is level in all directions - re-install pool
No. You can raise the PH level in your pool with Borax. I use it.
Masonry Sand is used to level the bottom of a pool
So that the water doesn't drain out of the pool and so the pool doesn't fall over. I agree with the answer above but I have a more detailed answer. In a round above ground pool the water puts even pressure on the pool walls, and if the ground is not level one side will get more pressure. The imbalance will cause the pool to collapse under the strain.
I just put up an above ground pool and we used sand to level the ground. To level the sand, we used one of those string levelers and tied it to stakes on each side of the pool area to make sure it was all level.
If this is for an above ground swimming pool, I would level the ground before putting up the pool. Otherwise, the weight of the water might collapse one of the walls of the pool.