Low system pressure

[rbienert]

Hi.

Since a few weeks I am battling low pressure in my pool system. At times, the pool pump can't even get over the priming cycle (Sta Rite Variable Speed, 2-3 years old). Interestingly, the pressure varies throughout the day as if something seals a bit better when the sun warms it up (sounds weird, I know). So in the mornings I often get barely any flow going whereas in the late morning or afternoon I get up to maybe 8 PSI (before this problem, I had usually around 15+).

So far I have tried all of the following:
- Cleaned skimmer and trap baskets
- Made sure no blockage is within reach (skimmer, etc.)
- Replaced Trap o-ring and intake flange o-ring on pump (I used o-ring sealer, too)
- Dis-assembled Jandy valve and re-applied o-ring sealer (o-rings look like new)
- Opened pump, checked for debris in impeller etc.. and checked o-rings (one small and one large in the Sta Rite). Looked good and re-assembled with o-ring sealer
- One after the other, taped pipe joints with heavy duty electrical tape to maybe identify any leak. I assumed that while this would not entirely fix it, it should at least show me a small variation in pressure.

So I am out of options that I can think of. It also puzzles me that the pressure changes for unknown reasons. The only next steps I see are:

- Take the pump out and bring it to a store that can check it, or
- Apply pressure to the system to find the air leak

Both seem to be a major pain in the neck so I am hoping to get some additional clues.

Thanks!

[PoolDoc]

It sounds like you have a suction leak. Is there air in the pump basket when the pump is on?

[rbienert]

Thanks for reading my post PoolDoc.

The flow into the pump basket is very limited. So it doesn't even fill up completely. Yesterday morning I had about 1-2 PSI, later in the day it built up to about 6-8 but the pump basket is still not entirely full.

[PoolDoc]

Suction leaks are hard to find. Common locations include:

+ pump basket lid gasket
+ threaded connection to pump
+ unions
+ valve stems
+ cracks in piping
+ 'stuck' skimmer weir flaps (not a 'leak', but still brings air into piping.)