Air bubbles in the pool pump basket: finding the air leak
Updated : · Piscines VP
Bubbles in the strainer mean air is getting in on the suction side, before the pump. Most common causes: low water level, dry or damaged lid O-ring, loose or cracked suction fitting, a valve letting air in. Air makes the pump work harder and hotter and can cause cavitation.
A strainer full of bubbles is a pump pulling in air along with the water.
Causes, most common first
- Water level too low: the skimmer sucks air.
- Lid O-ring dry, dirty, cracked or misplaced.
- Lid cracked or not tight.
- Suction-side fitting loose or cracked (union, threaded adapter).
- Pump drain plug loose or missing its gasket.
- Worn suction valve.
- Worn shaft seal (rarer, often with a water leak).
The shaving cream trick
With the pump running, put a little shaving cream on the suspect fitting or seal. If it gets sucked in or dents, that’s the leak.
Why fix it quickly
- The pump works harder and runs hotter. See Overheating pump.
- Air can cause cavitation (gravel sound). See Cavitation.
- Filtration is less effective.
- A sand filter may blow bubbles back into the pool.
Frequently asked questions
A few bubbles at start-up, is that normal?
Yes. At start-up the pump pushes air out of the plumbing. Bubbles should disappear after a minute or two. If they stay, there's an air leak.
How do I find an air leak on a fitting?
With the pump running, put a little shaving cream on the suspect fitting: if it gets sucked in, you've found the leak.
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