6 Places to Check When a Pool Pump Loses Prime

Pump lid o-ring This single rubber ring causes about 80% of prime-loss problems. Remove it, clean it, lubricate it with silicone pool lube, and reseat it properly.

Drain plug on the pump housing Check if it is loose or missing its o-ring. A small air leak here will break the prime.

Skimmer weir door A stuck-open weir door lets air into the suction line. Make sure it moves freely and seals when the pump is off.

Pipe fittings and PVC joints Inspect all suction-side connections for cracks or loose fittings. Even a hairline crack in the PVC will let air in.

Water level in the pool Low water causes the skimmer to suck air instead of water. Keep the level at least halfway up the skimmer opening.

Use a hose to find hidden leaks Run the pump and spray water over every joint and seal. When the motor sound changes or the pump starts priming, you have found the leak.