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.
Unfortunately, no. If the sand isn't level when you put the pool on top of it, the bottom of the pool will stay uneven after it's filled. Sorry.
SAnd is used in sand filters. rocks are not used in pool filters.
Silica sand has glass in it, and it is not to be used in pool filters. You will get the best results when using pool sand.
sand
You don't use sand to level the ground that the pool sits on. The sand is used on the inside of the pool, after the ground has been leveled by taking the highest point down to the lowest point after the grass has been removed. The manufacturer's usually recommend 2" of sand on the inside of the pool before the liner is installed. It sounds like you are installing a used pool, since you do not have instructions. Here is a link to some instructions that could possibly be used. http://www.royalswimmingpools.com/install.htm
You will need to level the area under the pool, though. Most suggest using sand to do this.
Don' know how to store used filter sand, but a good question none the less :)
Usually the top of the sand filter is above the water level of the pool, so all you have to do is unscrew the top and look in. However if the filter is below the pools water level you will have to cut of the water coming from and to the pool before you do. who added the sand? If you did - did you follow the manufacturer's instructions as to how much and what type of sand to use? Instructions tell you - - SPECIFICALLY - - how many pounds of # 20 silica sand to use.
It is best to use a fairly clean sand, like washed river sand shy away from a loamy sand as used by bricklayers.
If you have a sand filter the laterals in it may be starting to show signs of wear these wil blow sand from the sand filter into the pool when they wear out.
You must remove all the sod where the pool will sit. Remove 2 inches of your sod from this area. Rent a sod cutter for a 2 hour period. Pack down the dirt or let it settle for a few weeks before you continue. Order enough sand for the hole to make the area completely level. Use a straight 2x4 (one foot longer then the length of half the circumferance of the pool) ie 15' pool use 8 or 10' 2x4. Use a level on the top of the 2x4 all around the sand area. The area is ready for the pool. This is the BEST way to prepare for the pool.