How to Prime a Pool Pump and Why It Keeps Losing Prime
Priming fills the pump and suction line with water so the impeller can create steady flow. If the pump repeatedly loses prime, the real problem is usually low water, a restriction or air entering the suction side.
Before trying to prime
- Check that the pool water is at its normal operating level.
- Empty the skimmer and pump baskets.
- Confirm the suction and return valves are correctly positioned.
- Inspect the pump lid seal and sealing surface.
- Make sure drain plugs and unions are secure.
How to prime a typical pool pump
- Turn the power off.
- Open the pump lid and fill the basket housing with water.
- Clean and reseat the lid seal, then secure the lid.
- Open the filter air relief if the manufacturer directs.
- Start the pump and watch the basket fill.
- Close the air relief once a steady stream of water appears.
- Check return flow, gauge pressure and visible air bubbles.
Equipment and valve layouts differ. Follow the pump and filter manuals where they conflict with a general procedure.
Why it keeps losing prime
| When it happens | Possible cause |
|---|---|
| Immediately after starting | Low water, closed valve, blocked line or major air leak |
| After several minutes | Intermittent suction leak or restricted skimmer flow |
| After the pump stops | Lid seal, union, check valve or plumbing allowing water to drain back |
Air bubbles are useful evidence
Bubbles under the pump lid or continuously entering through return jets suggest air is being drawn in before the pump. Water leaking from the pressure side is a different issue.
When to stop troubleshooting
If clean baskets, correct water level and a sound lid seal do not solve it, the impeller or suction plumbing may need inspection. Repeatedly forcing a dry pump to restart risks seal damage.
Want the system checked properly?
Pool Perfectionists services and upgrades pumps, filters, chlorinators and pool heating across Sydney, with local technicians based in the Sutherland Shire.