I have been working on a neighbor's pool for the last 9 days SLAMming the algae problem. My trouble now is that the skimmer basket is no longer moving water, and there is air in the pump basket and through the exit jets. Both suction side valves are old and I have used the skimmer valve several times in the last week. I believe it may have failed. I closed it to partially drain the pool 2x over the week because of very high CYA. At the time when I was draining, and the water reached a certain point below the jets, the pump quit sending water to waste and I turned it off. The skimmer basket valve was closed but was making a sucking gurgling noise as if letting air in.
I also started adding DE to the sand filter yesterday to help clear the water. Maybe that pushed it over the edge. I was careful to add 1/4 cup and watch filter pressure, not adding more than 3/4 cup total.
I checked the pump lid gasket and it looks ok. If the valve is the problem then I can replace it but will have to dig into the cement as the base of the valve is at ground level and I can't see another way to add a coupling and another valve.
As a test, I closed the drain valve to see if water would move in the skimmer but it doesn't.
Also, as I close and open the skimmer valve it changes the air flow to the pump basket, but no water flow to skimmer. It also changes pressure gauge by a couple of lbs.
Is this just a valve problem or something else?