How to Identify and Correct Air Leaks

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If you are seeing a significant number of bubbles coming out of your return lines into the pool, you probably have an air leak in your filtration system. Possible sources of this problem are low pool water levels, leaks around the strainer lid, leaks in the unions or leaks in the pump seals. For optimum pool pump operation, the source of the leak must be identified and corrected.

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Step by Step

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Step 1

Your swimming pool filtration system has two sections: the suction side (from the pool to the pump) and the discharge side (from the pump to the pool). Check the strainer pot of your pump. If you see a significant number of air bubbles moving through the strainer pot, you know that the air leak is somewhere on the suction side of the system plumbing before or at the pump.

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Step 2

The ideal water level should be at least halfway up the skimmer intake. If the water level drops below that level, the skimmer can start to gulp air with the ebb and flow of circulating water.

This simple problem has a simple fix: add water. Drop in a hose, and get that water level up. Keep an eye on it in the future to prevent a reoccurrence. A simple add-on feature is water levelers, that make sure your water is always at optimal levels.

Step 3

Before we begin the actual inspection of the plumbing elements. Switch off the master breaker to your pool pump.

Release water pressure in the system using the air relief valve on your filter. The air relief is generally only found on Cartridge and De filters. Sand filters do not have this feature, so expect some splashing when accessing plumbing elements like the pump strainer lid, and unions.

Step 4

Pool Pump Strainer Lid O-ring; The pump strainer lid is sealed by a single gasket; which once it loses pliability can provide a direct route to foul your prime. Normal signs of wear are cracking in the rubber, warping or stretching, and the obvious, missing bits

Check the rubber gasket for cracks pinching the gasket into a smaller loop. Cracks will look like striations across the length of the gasket.

Warped or stretched gaskets are evident when the o-ring sits in the groove o-ring, spilling over. The warping of an o-ring can lead to it being pinched creating a gap through which air can enter the plumbing.

If necessary, replace with new gasket, after cleaning the o-ring’s groove of gunk and leftover lube. Apply a new coat of lube, as well.

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Step 5

Your pump housing’s drain plugs are often overlooked when diagnosing an air leak, but these little gasket-sealed ports cause havoc if the seal is broken. Use any of the air leak techniques mentioned above or do an eye inspection for a pinched or defective gasket.

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Step 6

If your pump strainer gasket wasn’t the issue, move forward to the pump union. Most pumps have a union on their intake, this allows for easy maintenance and removal. These unions have a single gasket that seals the cuff and screw on adapter. Most commonly these o-rings become pinched. Go through the checks of the o-ring mentioned in the previous step

Step 7

PVC plumbing glued joints like tees, elbows, and valve ports are another common culprit. The epoxy sealing these joints can become brittle and washout overtime. This can create a progressively worse and worse air leak leading to complete pump priming failure.

The smoke, soapy water, or shaving cream method is the standard way of finding these leaks. Repair can be as simple as adding a caulk patch. Or if you want to ensure a permanent fix, re-piping and gluing will be necessary.

Step 8

If your air leak problem only occurs when you attach your vacuum hose, then the issue maybe pinhole-sized leaks in one or multiple hose sections. To find and replace these hose section:
  1. Disconnect all hose sections
  2. Use tape or plugs to seal the end of each section
  3. Submerge the hose section, while looking for any stray air bubbles coming from the body of the hose
  4. Complete this for each hose section, replace the sections with holes
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Step 9

If you still have a significant number of air bubbles coming out of your return lines into your swimming pool, you may have a bigger problem like leaks in your underground lines. Call a pool maintenance professional to help you isolate your problem.

Comments

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(1 to 40 of 563)

Anonymous  Posted: 9/7/2020 

I have air bubbles coming from my returns . After checking a few things and finding nothing , I shut one of the intake valves, the bubbles quit. I assume this means I have a leak in that line??
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InyoPools Product Specialist  Posted: 9/8/2020 

All the signs are pointing to that fact. I'd give that portion of plumbing a thorough once over to find the culprit.
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 Posted: 9/4/2020 

I'm at a loss as well. I have a new pool (2 years old) and Hayward 4820 and I just cleaned my grids and put recommended DE amount in and my filter pressure is sitting at 25psi. Flow rate is terrible on the pump side and the pump basket has about 1/3 at the top that I can't get rid of. I suspect an air leak somewhere on the suction side but I can't find it for the life of me.
 Reply

InyoPools Product Specialist  Posted: 9/8/2020 

Have you tried setting your filter valve to recirculate or whirlpool so that the water bypasses your filter? This is just to see if the filter grids or one of the internal pieces is playing a part in the flow issues.Another thing to check is to set the filter to normal filter mode but try setting your diverter valves to only pull from the main drain or the skimmer to see if you can narrow it down that way.
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 Posted: 9/2/2020 

I have a salt water pool 48 sqft de filter. The psi on the de filter was going to about 35psi after we back washed within a couple hours. We then bought new grids and replaced the old ones cause they was a little wore and had some breakage. So now the new grids are in place and on start up it had good flow and psi was about 18, within maybe 5 hours or so it was at 30 and there is an are bubble in strainer basket on pump side, plus the jets in pool have a reduced flow. Also on our pool display panel it says no cell power, and no cell power 2. Just trying to find out why we have high psi and hardly any flow. Pool is clear now but it seems like the algae is trying to grow back I guess from the slow flow. We have a hayward system that is about 5 years old, salt water pool about 18,000 gallons inground
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InyoPools Product Specialist  Posted: 9/3/2020 

How much DE are you putting in the filter after backwashes? The fact that algae is starting to bloom can also add to the filter's pressure issues. If you have no chlorine in the pool, the grids will become clogged with algae and other organic material. When the filter gets clogged, the water becomes stagnant, which leads to water becoming even more of a feeding ground. And the cycle gets worse and worse.It sounds like you need to troubleshoot your salt system, which will then alleviate algae problems, which will eventually lead to fewer pressure issues.
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 Posted: 8/31/2020 

I have a new variable speed pump, new DE filter. Water is clear but pressure on filter gauge never gets above 4psi. Been running a month now and started to get small bubbles and have to let air out of filter every couple days. Have run all the checks for air and leaks and have found none. Is all this normal?
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InyoPools Product Specialist  Posted: 9/1/2020 

At what RPMs are you running the pumping?
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 Posted: 9/1/2020 

Running pump at 2600 both skimmer and main drains open, averaging 23 GPM.
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InyoPools Product Specialist  Posted: 9/3/2020 

If you close the skimmer line, so you are only pulling from the main drain, does the pressure issue get better, worse, or stay the same?Does the pump lose prime every time it turns off? That is a sign air is getting in there somewhere. What is the model number of your pump and filter?
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 Posted: 9/3/2020 

The pressure stays the same with both open or one or the other closed. The pump has no problem with re prime. Takes about a minute. I have bleed the filter every time I shut off the pump. The filter is a Hayward DE3620. The pump is a Harris 1 1/2 hp variable speed. All pipe is 1 1/2 with long sweep 90s. Pump and filter are approximately 2 feet above the returns in the pool.
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InyoPools Product Specialist  Posted: 9/9/2020 

If you have personally checked every piece of plumbing (suction and pressure side), and are unable to find the air leak, then you should call a professional. Because either a specific element is being overlooked or there is something peculiar in your system. A pool's plumbing should be a closed system. The skimmers and main drain are underwater, as well as the returns. Air wouldn't be able to get in there. Pipes below ground can't pull enough air to cause your symptoms. The only culprit left is the exposed plumbing.
 Reply

 Posted: 8/5/2020 

If you have a salt water pool, try turning off the chlorinator at the panel. Check if bubbles still come out of the return lines. When chlorine is generated, it makes bubbles. I turned mine off and the bubbles went away within 15 seconds. I spent a lot of time trying to figure out my "leak" until my friend told me about this quick check.
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InyoPools Product Specialist  Posted: 9/9/2020 

The salt chlorinators I've seen in action usually doesn't create enough bubbles to cause much concern. But every little bit helps when trying to track down an air leak.
 Reply

 Posted: 7/5/2020 

No air in pump basket but air pocket and lower water than usual in my swag? Would the swag gasket do that? Air in return line also?
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InyoPools Product Specialist  Posted: 9/24/2020 

What is a swag gasket?
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Anonymous  Posted: 5/5/2020 

Hello I have bubbles coming out of only one jet. The either three jets are fine. What do I need to do?
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InyoPools Product Specialist  Posted: 10/27/2020  Latest

What troubleshooting steps in the article have you done already? 
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 Posted: 4/6/2020 

Hi there! I recently purchased a home with an older in ground pool, but new equipment. I noticed that the automatic pool cleaner wasn’t working through the slimmer. That quickly spiraled into noticing that when I close the main drain at the Jandy valve, limited to no water comes out of the skimmer line causing the pump to lose its prime. I’ve tried using a Drain King, large vacuum, and other tips but cannot seem to get the skimmer line to maintain pressure. I checked everything above ground and it doesn’t seem to have any leaks before the pump basket. I’m at a loss and would like some thoughts before I call uncle and have someone come out.
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InyoPools Product Specialist  Posted: 4/7/2020 

The only thing I would think of beyond your long list of methods already tried is adjusting the water level of the pool. if the water is even slightly too low on the skimmer will start chugging air leading to air issues.
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 Posted: 1/18/2020 

Over the 8 hours when the pump is not running, air is getting into the lines above pool water level. By the time the pump turns back on the lines are empty. After the pump restarts and primes, water flows normally and air bubbles eventually cease. There are no signs of water leaks anywhere. Is it possible for valves to leak air on the discharge side of pump when pump is not running, but still hold water when under positive pressure?
 Reply

InyoPools Product Specialist  Posted: 2/10/2020 

If the pressure side of the system (all pipe and equipment after the pump), there would be water leakage from the compromised point. If you follow the instructions in the guide of the smoke, soap or foam method we list in step 7 in the guide, you should be able to find the issue on the suction side.
 Reply

 Posted: 12/2/2019 

I don’t see bubbles coming in to the pool but the pump basket has significant air in it. I’ve done several air leak checks on the suction side but found nothing. Help!
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InyoPools Product Specialist  Posted: 12/4/2019 

Do you have a variable speed or two-speed pump? It is common for those pumps to have air in the strainer when run on lower RPM's.
 Reply

 Posted: 11/10/2019 

No bubbles in pump strainer yet bubbles coming from pool jets
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InyoPools Product Specialist  Posted: 11/11/2019 

Our guide lists several things to check. I would start with those.
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 Posted: 9/12/2019 

I see bubbles at the startup of the pump only and quickly go away, the pressure used to be around 15 psi but now it stays at 30. If I backwash the system the pressure goes down to 10-20 but gradually increases again back to 30. I cleaned the filters already and run the pool filter for 8-10 hours for 5 days and the water is cloudy and I still have the same pressure problems.
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InyoPools Product Specialist  Posted: 9/12/2019 

It sounds like you have completed one of the parts of troubleshooting mentioned in the guide. If you haven't already, I suggest following the other steps to find the air leak. This is not something that can be diagnosed purely by a brief description of the problem; you have to do the troubleshooting on-site.
 Reply

 Posted: 9/10/2019 

my pool pump stopped working suddenly. when in "filter" it has no suction, however when in "backwash" it sucks nicely, on rinse suction is less, on bypass no suction.
 Reply

InyoPools Product Specialist  Posted: 9/12/2019 

Going by that brief description, it sounds like you have a dirty or clogged filter. If the sand is a few years old, then you may have to change the sand if heavy backwashing doesn't fix the pressure issue.
 Reply

 Posted: 8/8/2019 

Hello, I recently installed an above ground pool 12x18 oval sand filter for my kiddies and not knowing anything about pools once the pool filled up I turned on the filter instead of backwashing it first causing the water to get cloudy...how can I get rid off this cloudiness in the water? First timer here and I have no idea what to do!
 Reply

InyoPools Product Specialist  Posted: 8/8/2019 

If the cloudiness is due to sand, you can wait for it to settle to the bottom of the pool then vacuum it up. If you think there is a chemical imbalance causing this issue, I would test the water to determine the steps needed to correct it. The fix could be as simple as adding some clarifier or adjusting your calcium hardness levels.
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 Posted: 8/7/2019 

What can be done if only one of the 4 return inlets have an air leak and poor flow?
 Reply

InyoPools Product Specialist  Posted: 8/7/2019 

have you checked any of the things mentioned in this guide? That would be a good place to start.
 Reply

 Posted: 7/8/2019 

Hi--how ofter do you need to replace an impeller? pump comes on but water wont circulate at all. no leaks I can determine.
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InyoPools Product Specialist  Posted: 7/9/2019 

Impellers only need to be replaced when they are broken. You may want to try reviewing this guide: How to Correct Low Water Pressure in Your Pool System
 Reply

 Posted: 7/3/2019 

Good morning. Water was exiting through my backwash hose during filtering and there was low pressure. I was told that it was most likely a faulty valve. The valve was roughly 7 years old. I replaced the valve (from INYOPools) and the same thing is happening. Water also runs out of the backwash hose when turning the handle to a different setting. On recirculate, the pressure is fine and no water exits through the backwash hose. I'm hoping you can tell me what the problem is here because I'm lost. Thank you!
 Reply

InyoPools Product Specialist  Posted: 7/3/2019 

A few things to check: Is the handle stiff or jiggly? A loose handle is the sign of a bad spring.If you open the valve, is the spider gasket still intact and secure in the groove? If not, then this may be the cause of the flow to the backwash.
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 Posted: 6/27/2019 

I seem to get air in lines but only when the skimmer inlet is used. The water level is perfect, psi with only bottom drain is 15, add in skimmer it jumps to 18. All normal, but air somehow gets in and psi starts dropping when skimmer is added.
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InyoPools Product Specialist  Posted: 7/3/2019 

The article mentions checking the pipe joints on the plumbing line. Since you have narrowed it down to the skimmer line, you can start there.
 Reply