Filtration & Circulation /
How to Open the Air Relief Valve on a Pool Filter
Shut off the pool pump first, then slowly open the air relief valve until air escapes and water flows steadily. If it sticks or sprays, stop and call a pro.
Archive date: this article was written for PoolSkimmer on Oct 24, 2026 and given the earlier archive date of Apr 21, 2026 so the blog reads as an organized archive. It was not published on that date.
The safe way to open an air relief valve
The general rule for most pool filter configurations is to shut the pump down and then slowly open the air relief valve. You want to let any trapped air out until you see a consistent flow of water. Do not attempt to open it with the pump in operation or put force on a valve that is stuck; always defer to your pool filter manual for the precise procedure.
Precautions before you begin
It is wise to ensure the pool equipment is in good order before handling the valve. Verify the pump is off and not running. Have a look at the pressure gauge for anything amiss and check for hot spots, cracks or leaks. Put on some PPE like gloves and eye protection if the area is warm or soiled, and be sure to keep your hands and face clear of the discharge.
Should you find the filter tank is compromised, the valve is cracked or there is a significant leak, put down the tools and get a qualified pool professional on the phone.
Dealing with the top-mounted valve
You will often find the air relief on the lid assembly or at the very top of the filter. Make of the design can differ from one brand to another – Pentair and Hayward models are case in point – so the manual is your guide.
Proceed in this manner:
1. Switch off the pump and give it a moment for the pressure to even out. 2. Position yourself to the side of the unit rather than over it. 3. Gently crack the valve to let the air hiss out. 4. Leave it open until the water runs steady and unbroken. 5. Give the valve a firm close without overtightening.
Whether it is a knob, a lever or a screw-cap, use only the motion the manual prescribes. The manufacturer must tell you to remove the air relief valve before you do so.
The purpose of the valve
Simply put, the air relief valve is there to let trapped air out of the tank so the circulation system can do its job. Left in the filter, air will impede water flow, cause gurgling and make priming a chore. It is also useful to vent the system after backwashing or other maintenance work.
Persistent air?
When air shows up time and again in the pump or filter, the valve is likely not to blame. More often it is a sign of a blockage or leak in the equipment. Check for a loose O-ring or pump lid, debris in the basket, a skimmer with low water or a dirty filter in need of a backwash. Suction-side plumbing can also be the source of an air leak.
Time to call in an expert
There is no sense in trying to fix electrical or structural issues on your own. Put in a call to a pro if the valve is stripped, leaking or refuses to budge, or if the filter is losing prime on a regular basis. Erratic readings on the pressure gauge or a tank that is spraying water violently are also reasons to stand down. If you are in any doubt as to which valve you have, check with the manufacturer’s support or the equipment manual. A proper release of air is worth the extra care to avoid a hazardous or messy start-up.
Sources and further reading
- [Hayward: Weekly pool maintenance](https://www.hayward.com/maintenance/weekly-pool-maintenance)
- [Pentair U-3 skimmer manual: suction safety warnings](https://www.pentair.com/content/dam/extranet/nam/pentair-pool/pool-manuals/u-3-skimmers/395010028C.pdf)
- [SwimmingPool.com: Cleaning the skimmer basket](https://www.swimmingpool.com/maintenance/pump&filter/cleaning-the-skimmer&pump-basket)
- [CDC: Use pool chemicals safely](https://www.cdc.gov/healthy-swimming/media/pdfs/Pool-Chemical-Safety-USE-poster-p.pdf)
- [CPSC: Electrical safety in and around pools](https://www.cpsc.gov/safety-education/safety-guides/pools-and-spas/dont-swim-shocks-electrical-safety-and-around-pools)