Hayward pump works at 100%, 50%, but not 25%.

[SillyOleBear]

I know all my sand filter is basically clean and strainers and skim filter are free of any debris. The pump, in pool mode, works like a champ at 100% and 50%, but it dies at 25%. Last year it ran fine at 25%, but not this year. It occurred to me to do a deep cleaning of my sand filter. Does that seem like a likely cause for the pump to die at the lower setting? If not, any other suggestions? Oh, I should mention, the pressure reading on my filter unit is about 21PSI, and it doesn't seem to go down much at all even after basic cleaning. TIA.

 

[1poolman1]

I know all my sand filter is basically clean and strainers and skim filter are free of any debris. The pump, in pool mode, works like a champ at 100% and 50%, but it dies at 25%. Last year it ran fine at 25%, but not this year. It occurred to me to do a deep cleaning of my sand filter. Does that seem like a likely cause for the pump to die at the lower setting? If not, any other suggestions? Oh, I should mention, the pressure reading on my filter unit is about 21PSI, and it doesn't seem to go down much at all even after basic cleaning. TIA.

Which Hayward pump? Which sand filter? How large? Is something blocking a basket? Is the impeller partially clogged? What kind of pool?