Purchased a new home in Pensacola in August 2014, with inground vinyl pool, shape of a stop sign. This is our 2nd pool, first was rectangle fiberglass inground. new pool has SWG and sand filter, unlike other one that had cartridge and liquid chlorine. Previous owner left us zero operating manuals.
Anyway, filter pressure indicator had water inside, so I replaced it. Got same pressure readings of about 10psi. Sight glass on filter had a tiny bit of sand, but no water in it. Water in the pool nice and clear since day one, so I only added salt when required.
Finally decided to backwash just for the heck of it. After all, the pressure gauge still at 10 psi. OMG was the water dirty. Looked like the muddy Mississippi River coming out the hose for a few seconds.
Guess I need to backwash more often. Should the sight gauge always have water in it?