The level at which the swimming pool skimmers operate best is between
one third and one half the way up the opening of the pool skimmer. If the level
is higher, the water moving into the skimmer is going so slow that debris may
pass by the opening without being pulled in. If the pool water is so high that
it covers the skimmer opening, floating debris can't get in. If the water is
too low the skimmer can bottom out, thereby sucking air into the system which
can result in losing the prime and possibly result in burning up your swim pool
filter pump motor. Add water before back washing and vacuuming the pool because
this will also lower the water level.