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.

Video

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 575)

Anonymous  Posted: 7/19/2021  Latest

I have a pool that is less than a year old. When the pool was brand new we set the pump to around 2,300 rep and the return water filter and jets had good pressure. However recently I have noticed that at 2,300 the return output has decreased substantially such that instead of a decent waterfall it turns into a trickle. The PSI is around 10 to 12 PSI so not that high but higher than when the pool was new. Also when the pump turns on , it operates normally with a decent return and over time it degrades to a trickle? What could the problem be? I have checks the leaf basket as well as the basket in the pump. no issue there.
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InyoPools Product Specialist  Posted: 7/20/2021  Latest

This doesn't sound like an air leak problem. You either need to clean your filter, your baskets, or the impeller if it is clogged. More info - How to Correct Low Water Pressure in Your Pool System
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 Posted: 5/22/2021 

I have air bubbles coming from two of the return jets whenever my variable speed pump is set to less than 67%. None when its higher. When its at 55% and lower it gets more and more air the lower I set the pump rate. Does this mean there is still an air leak? Or is this a normal side effect of setting pump rate low??
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InyoPools Product Specialist  Posted: 6/4/2021 

At the lower speeds, there may be air bubbles that exit the jets. Do you happen to use a salt chlorine generator on your system?
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 Posted: 5/22/2021 

I tried for hours chasing down what i thought was a suction side leak, tore apart valves, pump inlet and cover, it would work fine for like 2 minutes and then the bubbles would return... strange thing was it got better at higher pump speeds... it finally clicked for me and I remembered that my salt water chlorine generator creates chlorine and hydrogen in gas form and that was the bubbles I was seeing! turned off the chlorine generator and wouldn't you know about 30 seconds later I had zero bubbles!
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InyoPools Product Specialist  Posted: 6/4/2021 

Oh jeez, that is relieving and frustrating all at the same time. Good job, ferreting out the problem.
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 Posted: 5/20/2021 

I keep getting high pressure on the filter/low flow return, the de cartridges look ok every time I open up the tank and they are only a year old. When I run the pool on RECIRCULATION the pool flow does not slow down, if I had air leak on suction side, wouldn't the flow also get worse while on RECIRC., or is this due to the air being trapped in the tank only ?
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InyoPools Product Specialist  Posted: 5/21/2021 

 This is not an air leak you are describing; you have dirty grids or charge the grids with too much DE causing a blockage. If there was trapped air in the tank, you would have been able to release it by opening the air relief valve.
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Anonymous  Posted: 5/24/2021 

How do you clear the grids if there is too much DE powder?
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InyoPools Product Specialist  Posted: 6/4/2021 

The filter should be backwashed to clear the grids of DE powder. For an example, look at this guide, How To Backwash a Hayward DE Filter.
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 Posted: 3/8/2021 

We have an in-ground Chlorine pool (8’ x 25’). For the past five plus years we have run the pump/filter system from 8:00 AM to 4:00 PM daily, and from 2:00 AM to 4:00 AM we run the system with the Polaris vacuum. Last Wednesday morning around 3:30 AM, I woke up and heard a strange noise. I looked outside and the pool was half full. I went outside, turned off the pumps, and noticed the drain plug on the filter assembly had blown out, obviously lowering the pool water level. The preceding Saturday I had cleaned the filter cartridges. Cartridges were purchased in May 2020. I clean them every three months. Air was bled out after cleaning. Normal System pressure: 20 PSI After investigation, the threads were stripped, on the filter assembly, where the drain plug fits. On Saturday, I replaced the bottom portion of the filter assembly and also installed a new gasket between the top and bottom of the assembly. I ran the system, with the Polaris, for about four hours on Saturday, and ran the pump/filter system all night through Sunday at 4:00 PM, with no obvious problems. During the time the Polaris was running, I noticed it was much slower than normal and the Polaris pump was leaking quite a bit. This morning (Monday), around 3:30 AM, my wife woke up to hear an unusual noise again. Once again, the pool level was down, below the skimmer. I ran outside and it appears the gasket between the top and bottom filter assembly failed, as water was spraying out. It appears that something is over pressurizing the system, causing two failures within four days of each other (drain plug and gasket). I have no idea what it could be. Does it have something to do with the Polaris, or is the leaky Polaris the result of the higher system pressure? Looking for ideas on areas to investigate. Thank you.
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InyoPools Product Specialist  Posted: 3/12/2021 

So we know what the normal operating pressure is, but what is the pressure when the pump is operating after an hour or so? Another question, when you complete your maintenance on the pool, cleaning cartridges and the like, is it in the evening after the day schedule has stopped? If that is the case, your filter is having pressure issues, but they aren't arising until the middle of the night because that's when the pump runs. You should let the filter run while you can keep an eye on it to see if you can spot what is causing these issues.
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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.
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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.
 Reply

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.
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 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.
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 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 

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?
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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.
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 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.
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 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