UV Pool Air Relief Valve Cleaning: Release Trapped Air Before Flow Drops
| September 4, 2026
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An air relief valve is small, but it has an outsized effect on UV pool performance. When trapped air sits inside the filter tank, the pump can lose steady pressure, the UV chamber can see uneven flow, and sanitizer demand can climb even though the equipment appears to be running.
Check the air relief valve whenever the filter pressure jumps after startup, bubbles return to the pool, or the pump basket never looks completely full. Confirm the water with a reliable test kit, then use the Pool Chemical Calculator, iPhone app, or Android app to adjust chlorine, pH, alkalinity, calcium hardness, and stabilizer from measured results.
Air relief valve warning signs
- Air hisses for a long time each time the pump starts.
- The filter pressure gauge bounces instead of settling into a steady reading.
- Return jets spit bubbles after the system has already primed.
- The valve drips, crusts with scale, or feels stiff when opened.
- Flow through the UV unit weakens after filter cleaning or basket service.
Why trapped air hurts a UV pool
UV sanitizers depend on consistent circulation. Air pockets can interrupt that consistency by reducing the amount of water moving through the filter and UV chamber. Even short periods of weak flow can leave debris, sunscreen residue, and organic load in the water longer than they should be.
Trapped air also makes chemistry harder to interpret. If flow is unstable, chlorine readings may look low in one area and normal in another. Fixing air problems first keeps the circulation system honest, which makes every chemical correction more reliable.
How to clean and check the valve
Turn off the pump before opening the filter. Slowly open the air relief valve until pressure is released, then inspect the valve stem, cap, O-ring, and seat for scale, grit, or cracked rubber. Wipe accessible surfaces with a damp cloth and replace damaged O-rings instead of forcing a stiff valve closed.
After service, restart the pump with the valve open until a steady stream of water appears, then close it gently. Watch the pressure gauge and return jets for several minutes. If air keeps returning, inspect the pump lid gasket, unions, drain plugs, and suction-side fittings before blaming the UV unit or adding more chemicals.
Recommended pool maintenance supplies
As an Amazon Associate, UV Pool Filter earns from qualifying purchases.
Keeps leaves and debris from starving the pump, filter, and UV chamber for water.
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UV helps supplemental sanitation, but chlorine, pH, and alkalinity still need testing.
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A clean cartridge helps protect flow through UV equipment and clears cloudy water faster.
View on AmazonFrequently Asked Questions
Should I open the air relief valve every time I clean the filter?
Yes. Releasing trapped air after filter service helps the tank fill properly and gives the UV system steadier flow.
Can a dirty air relief valve lower UV sanitizer performance?
Indirectly, yes. If trapped air reduces circulation, less water moves predictably through the UV chamber.
Why does my pool keep blowing bubbles after I bleed the filter?
Persistent bubbles usually mean air is entering on the suction side, often at the pump lid, unions, drain plugs, or skimmer line.