There is an air leak (suction leak) in the underground pipe between the weir (skimmer box) and the pump, causing the swimming pool pump to lose pressure. The connector fitting at the weir or the pump could be loose or perished. The shaft seal in the pump could be cracked and leaking. The filter sand could be clogged.
Beside this, how do I fix my pool pump suction?
Also to know is, what causes a pool pump to lose prime?
Debris blocking the suction strainer or foot valve is the most common cause. A blockage in the intake line can cause the water in the pump casing to overheat and literally boil out of the casing causing the pump to lose prime.
Why does my Hayward pool filter lose pressure?
It could be a clogged pump basket, impeller, pipe, or skimmer basket. It could also be a closed or broken valve before the pump. In some cases, the pump may have an air leak and is drawing in more air than water. This can reduce filter pressure (and filtration ability).