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How to Bleed the Air From Pool Lines

When you’re reopening your pool after winter or have a brand new pool, it’s likely you’ll have air in the lines. You could also have air in the lines after doing some work on the pool equipment, like replacing the pump or filter.

So to get rid of air from the pool lines and pipes, you’ll need to bleed air from the pool’s system.

Here’s how…

How to Bleed Air From The Pool Lines

The trick to bleeding the pool lines of air is to start with all the line valves closed. With the pump running, very slowly open the valves to introduce air into the pump until the pump sucks out all the air.

Here’s a video showing you how to bleed your pool lines (pipes). Don’t let the title of this video fool you, it will show you exactly how to bleed your pool lines.

Or if you prefer written instructions, here’s a detailed step by step guide:

1) Turn Off The Pump and Pool Equipment

The first step is to turn off and cut off power temporarily from the pool equipment. This includes the pool pump and heater.

2) Prime the Pool Pump

Now make sure the pool pump is primed. Open the pump lid and make sure there is water in there. If it’s empty, fill it with water. You can find detailed instructions in our article here:
How to Prime a Pool Pump (Above Ground & Inground Pool)

3) Inspect Pump Lid and O-Ring

The pool pump lid is a very common cause of air leaks in the pool lines. If the cover is cracked or damaged, air can get in. So damaged covers should be replaced.

Also, there are o-rings positioned inside the covers. If the o-rings are cracked, dry, or loose, air will get inside the pump system.

Tip: lubricate dry o-rings with o-ring lubricant. You can find one for your pool pump here:

Lube Tube O-Ring Seal Lubricant
  • Extends the life of rubber seals
  • Creates a better seal & stops leaks
  • Suitable for pools, spas, autos, RVs, boats, plumbing

5) Turn The Multiport Valve to Filter

Multiport valves are common with Sand and DE filters. The valve is used for a number of functions such as backwashing, but here, we need to get rid of air from the pool lines. So turn the multiport valve to the filter position.

We have a full article on the various filter valve positions here:
What Do All the Multiport Valve Pool Filters Settings Do?

6) Turn on The Pump and Slowly Open The Valve(s)

After doing work on your pool or after winter, the valves in your system may be closed. But if you reopen them fully and switch on the pump, it may suck in a lot of air and lose its prime. So the way to deal with this is to slowly open the valves. Here’s what you need to do.

Turn on the pool pump. Then while the pump is running, VERY slightly open one of the valve(s). Start with the main drain. It’s important that you do this step slowly.

You’ll notice the pump gets noisy as it sucks the air out of the lines. After a while, the pump should catch up and fill up with water. Now you can further open the valve, but very slowly as before. Keep doing this until you’ve fully opened the valve and there is minimal air in the pump.

Repeat this for all the pool valves.

7) Bleed the Air from the Filter

On the filter canister or housing in your pool, you’ll see one or two air pressure release valves. With the pump running, the valve(s) should be opened until water flows out (20-40 seconds). Close it when done.

Here’s a full article on bleeding the air from your filter:
How to Bleed Air From a Pool Filter (answered!)

8) Check The Pump and Filter Pressure Gauges

After bleeding the air from the pool lines, check the pool filter pressure level. It should be 50-75Kpa (kilopascal) or 10 – 25 psi.

This shows that there is no air in the pool lines anymore.

Should Air Bubbles be in The Pool Pump During or After Bleeding?

During the process of bleeding the air out of your pool pump, you may notice a lot of air in the pump. This is completely normal. Make sure you very slowly open the valves one at a time. This will give the pump enough time to suck the air out of the lines or pipes but without losing prime.

After you have finished the pool line air removal process, small air bubbles in a pool pump are normal too.

pool pump lid
Shows normal amount of air bubbles in a pump

However, if large air bubbles appear in the pool pump constantly, it’s an indication that air is leaking into the pool pump system or you haven’t bleed the lines properly. You can repeat the bleeding process if this is the case.

Air Bubbles in Pool During or After Bleeding Lines

Sometimes you may notice air bubbles in the pool coming out of the return jets. Whilst you’re bleeding the lines, this is completely normal. The air is being sucked through the system and has to get out somewhere.

But if you notice you still have air coming out of the returns jets after the bleeding process is completed, you may have a problem. So why are excess air bubbles in there?

Why is There Air in Pool Lines?

Having air in your pool lines doesn’t always mean there is a problem. It’s normal to have air in your pool lines when reopening your pool after winter, in a new pool or after completing some work on your pool’s system. Whether that is cleaning or replacing the pump, opening the filter or fixing a leaking pipe.

As soon as you open the pool’s system, air is introduced into it. So if you’ve done any of these things recently, go ahead and prime your pool pump and then bleed the air out of the pipes and that should remove the air from the lines.

If you still have air in the lines, there are some other reasons. Here are the common reasons for that:

  • Low water level in the pool
  • Loose pool pump lid
  • Defective O-Rings or seals
  • The Pool pump drain plug isn’t sealing
  • Loose Pool pipe unions
  • Damaged Pool pipes

1. Low Water Level

This is one of the most common causes of having air in the pool lines. If the water in the pool is below the skimmer, the pump can suck air in through the skimmer. To fix this issue, fill up your pool with a garden hose so that the water level is 1/2 to 3/4 of the way up the skimmer box.

2. Damaged or Loose Pool Pump Lid

If your pool pump lid is not seated and fitted correctly, it will not fully seal. And if this happens, you’re going to get air in the lines.

Same with if the pump lid is cracked or damaged. Even a tiny crack in the lid or in the lid threads can allow air into the system.

3. Defective O-Rings or Seals

Your pool has many o-rings and seals. If these seals are damaged or perished or not seated correctly, they can cause air in your pool pipes.

Start by checking the seal on the pool pump lid. It’s very common for this seal to be worn out. If you notice any cracking, it has lost its shape or it is broken, replace it. When installing the pump lid seal, use seal lubricant to protect the seal and to form a better seal.

You can also check the seals in the unions for the pump and other line/pipe fittings.

4. Damaged Pool Pipes/Lines

Cracked pipes are not the most common cause of air in pipes, so you should check the other things first. However, they do crack and break. This can be caused by tree roots, putting a spade or a pickaxe through them when gardening, or just age.

To know more about the causes and dangers of air in your pool pump, check out this article on the website. It contains everything you need to know.

5. Loose Pool Pipe Unions

All the unions, which are the pipe connections, are possible sources of air leaks in your pool lines. It’s more common for an air leak to occur at a joint in a pipe, since this is the weakest part.

Make sure all of the unions are seated correctly and are tight.

Final Thoughts

Overall, having excess air in your pool pump or lines can affect the pool’s functioning. So always keep tabs on the pool pump and filter gauges to spot any increase in air pressure.

Whenever the pressure is more than 10psi, ensure to bleed the air. Also, always check the pool lines and plumbing for any crack or loose fitting that can cause an air leak.