Home » How to Bleed Air From a Pool Filter (answered!)

How to Bleed Air From a Pool Filter (answered!)

Having excess air in your pool filters puts your pool equipment at risk of damage due to restricted water flow. Luckily, this post reveals expert strategies to bleed air from your pool filters. Let’s dig in.

When to Bleed Air from a Pool Filter

A pool filter should be bled of air each time air has been allowed into the system. That is, when the filter has been cleaned or opened or the pump basket has been cleaned. Another time to release and bleed the air is when the pressure is 5-10 psi higher than normal.

Many pool filters have internal mechanisms to prevent overpressure, but you shouldn’t rely on this alone. Pool filters are with an air-relief valve to get rid of the pressurized air.

And most filters have this air relief valve positioned at the top of the filter housing.

Every Two Weeks

If in doubt, you can bleed your pool filter every two weeks. It won’t hurt to open the valve, and it won’t cause any other issues. It’s just good practice to ensure the air is out of the system. This helps to prevent dangerous pressure build-up in the pool filtration system.

After Cleaning the Filter or Pump

It’s very important to bleed the air from your filter each time you open your pool’s filter. Opening the filter allows air into the system. This needs to be removed when you start the system back up.

You’ll also need to bleed the air out after cleaning out the pump’s basket. Opening the pump lid will, again, allow air into the system.

As well as taking in air when the pool filter and pump are cleaned, your pool’s water also contains tiny air pockets that build up. This air is sucked into the filter.

When There is a Buildup of Pressure

You can check the pool filter pressure gauge. If the filter pressure gauge reads more than 5-10 psi above the normal reading, you should bleed the air. “Normal” pressure from varies from pool to pool. It’s a matter of knowing your own pool.

Pool manufacturers know that air is bound to get in the pool filters whenever you clean and backwash the pool filters and open up the pool pump.

Let’s check out how to do bleed air from pool filters.

How to Bleed Air from a Pool Filter

To make this guide more helpful, let’s group the instructions into different filter types:

  • Cartridge Filters
  • DE Filters
  • Sand Filters

The basic methodology is similar for many filters, but the position of the air bleed valve does vary between models and manufacturers. And how to open the valve varies a little too.

Where is the bleed valve located? The pool filter air bleed valve is most commonly located on the top of the filter. It can also be located on the side.

How to Bleed Air from Diatomaceous Earth (DE) or Cartridge Filter

  1. Turn on the pool pump.
  2. Check the pressure gauge and note the pressure.
  3. Locate and turn the air bleeder valve(s). It’s usually an anti-clockwise direction (to the left) but can vary. The bleeder valve(s) are located at the top or side of the cartridge filter housing.
  4. Wait till water gushes out of the air bleed valve (this takes a few seconds). This means the air has been forced out (or bled).
  5. Damaged bleeder valve(s) should be replaced. Loose bleeder valve(s) can be sealed with plumber’s tape.
  6. Close the air bleeder valve(s) tightly.
  7. Check the pressure gauge. The air pressure should have reduced.

How to Bleed Air from Sand Filter

For sand filters designed with an air relief valve, turn the pump on, locate and turn the relief valve. Close the valve again after water flows through it.

Some sand filters don’t have a pressure release valve at the top of the canister. To get around this, you can do a DIY installation of a bleed valve.

To bleed air out of such sand filters, you’ll need to purchase an air relief valve.

Pentair Air Relief Valve
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Why is there Air in My Pool Filter?

Cleaning out the pump basket is the most common reason for air in a pool filter. When the pump is restarted after cleaning, this can suck air into the pool’s system cause air to get into the pool’s filter.

Normally, there shouldn’t be excess air or bubbles in your pool filtration system. But if you can see air in your filters or air is coming out of your return jets, this is the most common reason.

To remove the air from your filter (called bleeding), you will need to release the bleed valve on the filter for a few seconds until you see water running out. We have detailed instructions further in this article.

If this doesn’t fix the issue, here’s a number of other causes for air in your pool’s filter:

ProblemHow to Fix
Cracked or loose O-ring. Replace the O-ring.
Damaged Impeller. The impeller pushes water to the filter system. If the impeller is damaged or stuck, air can get in the filter system. Replace damaged impeller.
Loose pool pipe unions. Tighten and seal with plumber’s tape or replace pool pipe unions.
Low water level in the pool. Increase the pool water level with the hose.
Trapped air pockets (from when you cleaned the pool filters). Run the pool pump + bleed the filter.
Damaged pool pipes. Remove and replace damaged pool pipes.
Damaged skimmer. Replace worn-out or damaged skimmer baskets in the skimmer housing.
Multiport Valve Seals Bad Replace the o-rings and seals inside the multiport valve.
Reasons and fixes for excess air in pool filter.

We have a more detailed article explaining why you may have air in your pool and how to fix it here: Air Bubbles In Pool Or Pump | Causes and Dangers

Swimming Pool Filter System
Swimming Pool Filter System

Is Air in My Pool Filter Bad?

Excess air in your pool filtration system is not good for the pool equipment or pool and can be extremely dangerous.

There are several documented cases where pool filter lids have blown off, causing serious injuries including skull fractures and deep cuts. To avoid this, you shouldn’t allow air to build up in your pool filter. For more info on this, check out:
7 Tips to Prevent Pool Filters Exploding

In addition, if the air isn’t released from the pool filters, there will be poor water circulation through the filter system.

A poor water circulation means that there will be poor water filtration and cleaning too. If the pool water isn’t being properly cleaned, debris and contaminants will accumulate in the water. This could mean:

  • Murky or cloudy pool water
  • Possible bacteria and algae outbreak.

Other dangers of too much pressure in your pool filters include:

  • Burnt out pool heater.
    Pool heaters are usually located in the lines after the filter. If there is low water flow in the filter system, the pool heater will be starved of water and the heating mechanism can burn out.
  • Damaged pool filter

So when should you bleed air from the pool filters? Let’s find out.

How to Prevent Excess Air from Getting in The Pool Filter?

It’s almost impossible to stop air from getting into the pool filters entirely. But you can prevent the air pressure from getting to a level where pool equipment is at risk.


Bleed Air Regularly

You can prevent excess air in the pool filters by opening the air relief valve every two weeks to release air from the filter system.

Replace Damaged Skimmer Basket

Water flows through the skimmer basket before getting into the filter system. If the skimmer basket isn’t sitting properly or the skimmer weir is stuck, air could get into the filter system.

By replacing damaged skimmer parts, you are reducing the risk of high air pressure in the filters.

Ensure the Pump Lid is Sealed

Pump lids are a common cause of air in the pool’s system. Whenever you take the lid off, ensure it’s not cracked or damaged and the rubber seal is in good condition.

Tip: To prevent the O-ring from drying up and splitting, you should lubricate the O-ring with O-ring lubricant.

Lube Tube O-Ring Seal Lubricant
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When you put the pump lid back on, make sure that you don’t cross-thread it and that it is seated correctly. It should be straight and there should be minimal gaps between the lid and the pump housing.

Circulate the Water After Cleaning the Filter

When you take out the pool filters to clean, rinse, or soak them, you leave space for tiny air pockets to get in the filter system. When you return the pool filters, these air pockets will become trapped in the filter system.

But when water is in circulation, these tiny air pockets will come out as bubbles from the return jets.

So you should always run the pool pump to circulate water immediately after cleaning the pool filters.

Final Thoughts

Overall, having air in your pool filters isn’t good for the filtration system. But now you know how to prevent and bleed your filter to get the air out.

For more pool tips, check out other articles on the website.

Related Reading: How to Bleed the Air From Pool Lines