(1) I have a Hayward sand filter pump, I think maybe a 1.5 HP, but don't recall off hand. I had the motor replaced in Spring of last year. Afterwards, like always, I ran the pump 24/7 (except for a few minutes here and there when I emptied the secondary strainer basket at the pump) until last September when I covered the pool and then, like now, I ran the pump half days until October when the water cools down more. Last winter, as I will do this winter, I then just run the pump those handful of times when the outdoor temperature goes below freezing (thus, I never really close my pool, rather just cover it).

The same thing is happening now that happened all last winter. When the pump is off for a half day or longer, and I turn it on, the motor sounds like it's groaning. I do have prime, however. The jets are going as I can see the pool cover moving slightly. The secondary basket's o-ring is always replaced each year and I lubricate it often and the basket cover is very tight (no leaks). It sounds as if the impeller is struggling. I doubt it's impeded, because otherwise it would stay impeded.

After 5-15 minutes, the groaning stops and the motor hums perfectly like it should. While the motor is groaning, the pressure gauge sits at zero. During the time it's groaning, it slowly starts to climb. Ultimately--when the pump stops groaning and hums like it should--the gauge reads its usual baseline which is 20. During the summer season when I turn the pump off to clean the strainer basket then restart the pump, there is no groaning, just the perfect hum, so the groaning only happens when the pump has been turned off for a period of hours. I only backwashed twice this past 4-month season, once in the middle and once last weekend when I covered. And in both instances, my pressure didn't indicate I needed to (I use a leaf rake and vacuum up only fine particles), but it just seemed that I "should."

Any ideas? I'm trying to ascertain whether I should call a pool servicing outfit.

(2) On another note, is it necessary to run my pump/filter at all now, even though we still have outdoor temps in the high 80's? If you're wondering why I covered it so early, it's because in late August my pool only gets a few hours of sunshine because the position of the sun shifts and a huge pine tree blocks it out much of the day (if it shines) and the nights cool into the 60's and it's no longer warm enough to swim. Ironically, with the cover on, it will actually warm up now before it cools down. When I covered last weekend the water temp was 82 (by end of this week with lower outdoor temperatures it would've been several degrees cooler than that, although with cover the water temperature may actually exceed 82. Algae needs sun to grow, no? Of course I got it up to shock level which is about 15 for my pool. By the way, that CL level of 15 will drift down to only about 5 when I open in 8 months. Amazing.

I appreciate any comments!

Elsie