How to Bleed Air From a Pool Pump or Filter


Getting an air lock in your pool system somewhere is something you are probably going to frequently encounter but fortunately it is easy to rectify in most cases once you know how to get air out of pool pump.

The most frequent places you are likely to get air trapped are in your pool pump strainer or your filter housing.

To bleed the air from the pool filter there is normally a small valve at the top of the filter housing you can open to let out the air. To bleed air from a pump or strainer basket is less easy but by following a few small simple steps you will soon remove the air.

You will find a full explanation below.

How do you know if there is air in the system?

  1. You may be able to see air by looking into the clear lid of your pool pump strainer housing. If you can see water flowing from the inlet into the pool pump basket then it is not full of water (obviously). If you cannot see any water running then it is either completely full of water, so no air, or is completely full of air. If water is being pumped back into the pool then it cannot be full of air so it must be full of water!
  2. Your pool pump may be making a different noise (usually louder) than it does normally. It will do this when it is trying to pump air or just a small amount of water and air.
  3. There may be little or no water coming out of your pool outlets or waterfall if you have one even though the pump is operating on the filter or recirculate settings. This is probably going to be caused by an air lock in the system somewhere.
  4. If you are starting to vacuum you may have little or no suction.

How to bleed air from a pool filter

How to bleed air from a pool filter
air relief valve on pool filter

This could not be easier using the air relief valve on pool filter.

  1. Look for your air relief valve which you will probably find on top of pool filter housing, often just below or behind your pressure gauge. With air in the system the pressure gauge is unlikely to be showing a reading.
  2. With the pump running on the filter setting, slowly open the valve.
  3. If air is present in the filter housing you will hear air hissing out from the valve.
  4. Continue with the valve open until water starts to come out of the valve.
  5. Close the air relief valve on pool filter and that is the filter bled!

How to bleed air from a pool pump

If your pump strainer housing is full of air and after a few minutes of running the pump water doesn’t start to flow through it so it gets filled then you may have to help it. So to get air out of the pool pump try this:

  1. Shut off the pump and then close your skimmer lines using the inline valves. if you have more than one skimmer you may have individual feeds into the pump or perhaps just one (as I have on my pool).
  2. Fully open the bottom main drain valve (the line that comes from the drain at the bottom of your pool).
  3. Now start the pump and slowly open one of the skimmer valves a bit at a time.
  4. Hopefully you will start to see some air bubbles coming from the pool return jets which will be the air being pushed around the system.
  5. At this point you can try to remove any air that may be trapped in the filter housing by carrying out the procedure above.
  6. Once the skimmer valves are fully open you should have plenty of water going through the system and the air should be gone.
  7. If this still does not work then try the procedure below showing how to prime a pool pump.

How to prime a pool pump

If you have just filled your pool after emptying it for the winter then you may need to prime the system to purge it of air that will inevitably be there.

This is a pretty straightforward operation and I do it this way:

  1. With the pump off, move the multiport valve handle to the recirculate setting so water doesn’t flow through the filter but goes straight back to the pool instead.
  2. Take off the lid to the pool pump strainer housing.
  3. Using a garden hose, start filling the system through the strainer and let it run for a few minutes. This will start to fill the system through to the skimmers. If you can, push the end of the hose into the opening where water comes into the strainer from the skimmer. This would be the higher one of the two openings – the lower one goes to the pump. You may see air coming out of the skimmers which is good.
  4. Put the lid of the strainer back on firmly.
  5. Switch the pump on and run until you can see no air in the system.
  6. Shut off the pump and put the multiport valve to the filter setting before switching the pump back on.

Why might you have air in pool pump?

The most likely reason will be that you have just cleaned the pool and the action of stopping and starting the pump to backwash and rinse etc has allowed some air into the system.

You often have it when you first start to vacuum too. You can help to eliminate this by making sure you remove the air from your vacuum hose before you start.

If the water level in your pool is low so it is not covering the bottom of the skimmer then this will allow air into the system and is an easy fix of course by just topping up the water level with a hose.

If you have emptied your pool for the winter then you are likely to have air in much of the system. You may need to prime the pump to get it to start pulling water and any other air through the system.

You may have a leak in the lid of the pump strainer housing which could be letting in air. This could either be that you have not closed it properly when you removed it to empty leaves and other debris from the strainer basket or the o-ring in the lid may be faulty and need replacing.

The least likely (fortunately) is that air is getting in somewhere else in the system prior to it entering the pump. Check that any pipe fittings are not loose and letting air in. If you can’t find any then it may be a crack or similar in the pipework between the skimmer and the pump. If this is the case you are probably also losing water from the pool. Unfortunately I had this problem which resulted in lots of digging and the pipework being replaced (see below).

How to bleed air from a pool pump or filter

My top three pool cleaning tools to make life easier

Dolphin Nautilus CC Plus Robotic Pool Cleaner – the best time saving product on the market. I have never heard anyone say they regret buying one.

Hayward Poolvac Leaf Canister – very useful when leaves are a problem in your pool

Aquatix Pto Pool Step & Corner Vacuum Head – I use this every time I vacuum my pool. It gets where other vacuum heads can’t.

Is air in pool pump bad?

Yes. Having air in your pool pump is bad for two reasons. It will mean the filtration system cannot run at peak efficiency and also running your pool pump “dry” for any length of time will lead to it failing.

Why is my pool pump pressure high?

The most common reason why your filter pressure gauge will be showing a higher pressure than normal is that the filter is clogged with debris so back pressure is building up. The way to fix this to backwash. Read my guide How to backwash a filter step by step.

JP in Fuerteventura

I have had hot tubs for many years and a pool for the last 7 years. I had to learn how to clean it, maintain it and fix it the hard way. Since then I have helped many friends and neighbors with their pools and now I want to share everything I have learned with you.

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