Pump losing prime

[ashirley]

My pond has run for 7 years with minimal issues. The last two weeks have been a different story. For some reason my pump and my backup pump are losing the prime. It may runfor 20 minutes or 2 days but eventually they stop pulling water. My husband thought it was the bog but we bypassed the bog and continue to have the same issues. We can feel air on the outside of the shutoff valve above the pump. But this valve is in the outflow side not the intake. Does anyone have any ideas as we are at a loss? I don't believe it's the pump because I having the same issue with both pumps. The seals were recently replaced but they ran fine for a time.

 

[jmajid]

Hi,
Any photos of the pump/s and their plumbing? Are they the so-called self prime type?
Do you have a check valve on the system and if so is it something you can check to see if its operating? Also - what kind is it?
It's possible you have a leak on the inlet side of your pumps and that they are pulling in air and losing prime... have you checked your power to these pumps? Ensure its good and consistent?

 

[combatwombat]

Seconding what @jmajid said. If the pump is not self-priming and you don't have a check valve on your intake, you will lose prime any time the pump stops for even just a few seconds.

 

[ashirley]

Thanks! We replumbed the intake side of the pump and it is working better.