In ground vinyl pool has two skimmers (one of them far and weak) a return on the wall and a bottom return.
If both returns are open pool won't prime because there is air in the system. . So to start the pump I must first close off the bottom return. The pool then primes. But with only one return open pressure gets high in the tank and pushes sand into the pool. So I open bottom return, the pressure goes down and not as much sand in the pool. Any ideas? How can I figure out where the air leak is?