If you are talking about sand getting into the pool via the pool returns then you are probably in need of new laterals in your sand filter. These wear out every so now and then and need replacing.
Specifically where is it leaking? At the gasket? Replace gasket.
It already is used as pool sand!
Could be several things. If your pool walls are sunk into ground instead of setting on the ground, or pool is at base of a slope in the yard, and sand is washing out from under pool floor, it might just be a spot where heavy rains let water flow under pool wall and floor eroding the sand under the liner. Usually small pin-holes in the liner won't do much if anything to the sand, but if you get a larger hole in the liner, the water leaking out of the pool could also cause erosion of the sand under the liner.
The pool liner pad is placed underneath the pool liner to prevent items from cutting through the liner. If the liner is already leaking, the liner pad will not stop the leak.
The laterals inside are broken.
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.
For above ground pools you usually need at least 2" of double or triple screened sand. It is very important to have at least a 6" cove. The cove is where the wall and floor meet. The angle of sand is to prevent the liner from squeaking out from under the metal wall of the pool. If that where to happen the pool will eventually collapse
pool sand, preferably the sharp gritty stuff to catch the junk, NOT fine sand
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.
No they aren't
You don't . You chlorinate the pool with chlorine . You filter the water with a sand filter.
Maybe you just think its your pool and its really the beach. The beach has a lot of sand.