Pentair Clean & Clear Plus: Air Entering the Filter System
The Clean & Clear Plus manual treats air in the filter as a safety issue first. Pressurized air trapped inside the tank can cause the lid to separate from the tank body with force — the same hazard documented in the FNS Plus manual. The manual's troubleshooting section for air in the system begins with symptoms, then walks through five sources. All five must be corrected before the filter is serviced.
⚠ Air in a Pressurized Filter Is a Safety Hazard
Always shut off the pump before opening the filter for any reason. Open the Manual Air Relief Valve — turn counterclockwise until it snaps to full open — and wait until the pressure gauge reads zero. Never tighten the clamping system while air may still be present in the tank. The maximum working pressure of the Clean & Clear Plus is 50 psi.
Symptoms of Air in the System
- Low pool or spa water level: The skimmer throat is visible above the waterline or the skimmer is gurgling instead of flowing smoothly
- Air bubbles or low water level in pump hair and lint pot: Visible through the clear pump strainer lid — air pockets moving through the strainer indicate ongoing air ingestion
- Air bubbles at pool return lines: Fine or large bubbles exiting return jets while the pump is running
- Air discharged from the Manual Air Relief Valve when opened while the pump is running: The relief valve should discharge a steady water stream; if it discharges air first or continues discharging air, air is accumulating in the tank
Five Sources of Air Entry (From the Manual)
Source 1: Low Pool or Spa Water Level
When the water level falls below the skimmer throat, the skimmer draws air directly into the suction line. The pump transmits the air into the filter tank where it accumulates. This is the most frequently encountered and most easily resolved air source.
Correction: Add water to the pool or spa until the water level reaches the midpoint of the skimmer opening. Verify the skimmer is pulling a clean water vortex with no gurgling sound.
Source 2: Clogged Skimmer Basket
A skimmer basket packed with debris restricts water flow enough that the pump begins drawing air around the basket edges or through any small gap in the basket assembly. Even moderate debris accumulation can introduce air when flow is restricted.
Correction: Remove the skimmer lid and basket. Empty all debris. Check the skimmer throat below the basket for leaves or objects lodged deeper. Reinstall and confirm steady water flow through the skimmer.
Source 3: Split or Damaged Suction Cleaner Hose
If an automatic pool cleaner is connected to the suction side of the system, any crack, split, or hole in the cleaner hose provides a direct path for air to enter. The suction created by the pump draws air through the defect whenever the hose is submerged or on the pool surface.
Correction: Disconnect the automatic cleaner. Inspect the entire hose length section by section — pull each section apart slightly and flex it; cracks invisible at rest become apparent when the hose is bent. Replace any damaged sections. Reconnect only after confirming all sections are intact.
Source 4: Leak in Pump Hair and Lint Pot Lid
The pump strainer pot lid seals with an O-ring. A worn, cracked, or improperly seated O-ring allows the suction pressure created by the pump to draw air in through the lid joint. A cracked or deformed lid has the same effect.
Correction: Shut off the pump. Remove the pump strainer lid and inspect the O-ring — it should be smooth, pliable, and undamaged. Replace if cracked, flattened, or has any visible defects. Apply a thin film of approved O-ring lubricant. Inspect the lid itself for hairline cracks, particularly around the clamp groove. Replace the lid if cracked.
Source 5: Leak in Pump Suction Line
Any suction-side fitting, union, valve stem, or pipe joint that is not fully sealed will draw air under the vacuum pressure created by the pump. The air enters the system continuously at whatever rate the leak allows.
Correction: With the pump running, systematically inspect all accessible suction-side connections between the pool and the pump inlet. Apply soapy water to each union, valve body, and fitting — bubbles being drawn inward indicate an air leak at that point. Tighten loose unions, replace dried valve packing, or re-glue any pipe joints that have separated. Buried or inaccessible fittings may require pressure-testing the suction line to locate the leak.
Additional Check: Filter Inlet Union
If air continues entering the system after correcting all five sources, check the filter inlet union — the threaded connection where the plumbing attaches to the filter tank inlet. A loose or cracked inlet union is a less common but confirmed source of air on the pressure side of the pump.
Verifying the Fix
- Open the Manual Air Relief Valve before restarting the pump
- Start the pump and allow the system to fill and pressurize
- Close the relief valve when a steady, uninterrupted water stream flows — not intermittent spurts or air
- With the pump running, observe the pump strainer pot — no air bubbles should be visible after the initial startup purge
- Check the return jets — no bubbles after the first 30 seconds of operation
- Open the relief valve briefly a second time to confirm no residual air remains in the filter tank