How to Identify and Correct Air Leaks

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If you see many 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
  • leaks in the pump seals
The leak source must be identified and corrected for the most efficient pool pump operation.

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 many 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.

Click Here to View Replacement Pool Pump Parts 

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 gulp air with the ebb and flow of circulating water.This simple problem has a simple fix:
  1. Add water.
  2. Drop in a hose and get that water level up.
  3. Keep an eye on it in the future to prevent a reoccurrence.
A simple add-on feature is water levelers, ensuring your water is always optimal.

Step 3

Before we begin inspecting 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. An air relief is generally only found on Cartridge and DE filters. Sand filters do not have this feature, so expect some to splash when accessing plumbing elements like the pump strainer lid and unions.

Step 4

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

Check the rubber gasket for cracks, pinching it 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 the 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, allowing 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

Another common culprit is PVC plumbing glued joints like tees, elbows, and valve ports. The epoxy sealing these joints can become brittle and wash out over time, allowing air leaks that prevent the removal of all the air from the pump, leading to priming failure. This can create a progressively worse and worse air leak. The suction hose plays a crucial role in the priming process, and leaks in connections can prevent the vacuum necessary for drawing liquid up the suction hose to the pump, further complicating priming efforts.

The smoke, soapy water, or shaving cream method is the standard way of finding these leaks, and 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 may be pinhole-sized leaks in one or multiple hose sections. To find and replace these hose sections:
  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
Complete this for each hose section; replace the sections with holes.After checking the hose sections, consider performing a 'bucket test' to determine if your pool is losing water due to leaks or simply through evaporation. This simple method involves filling a bucket with pool water, marking the water levels inside the bucket and in the pool, and then comparing the two after a few days. If the pool water level drops more than the water inside the bucket, it's likely you're losing water due to a leak rather than evaporation. This test is great at helping identify whether you have a pool leak or if it is natural evaporation.

Click Here to View Replacement Vac Hoses

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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(281 to 320 of 604)

InyoPools Product Specialist  Posted: 11/8/2016 

Air in system - It sounds like you have a suction air leak. Try applying a soapy solution around any connection on the suction side of the pump including the pump cover and input port. Watch for soap bubbles being sucked into the leak.
 Reply

Anonymous  Posted: 11/7/2016 

Have a new waterway pump. I can prime the pump and it runs fine but in about 5 minutes there is air in the top of the filter basket almost to the top of the suction inlet but there are no bubbles coming from the jets. The pump continues to pump water throughout the day with the trapped air in the filter basket, The only other thing I noticed is a buildup of air in the filter, which i bleed off but it builds right back up. Is this normal for this pump, any suggestions on corrective action.
 Reply

 Posted: 11/7/2016 

just had cartridges replaced in filter. Service person put in five bags of shock to get rid of algae. Now I can't get any pressure on my gauge. Replaced gauge..still not working. The pump is working fine..no air bubbles..Water circulating fine. Pump is brand new
 Reply

InyoPools Product Specialist  Posted: 9/16/2016 

blodg - If you see water squirting out around the pump lid when you shut the pump off, that is due to backpressure. Such a squirt indicates that you do have a leak around the lid. Check for cracks in the lid or in the basket housing around the lid. If they are sound, I would replace the O-ring even though it looks good.
 Reply

 Posted: 9/15/2016 

That o-ring, although old and cracked, does not appear to be the problem. I tried the soap trick awa used smoke and found no suction any where around the lid (usually if that is sucking air, when the pump turns off, a squirt of water shoots out around the lid. I don't have a union in front of the basket. That only leaves the pump o-rings and the seals. What do you think?
 Reply

InyoPools Product Specialist  Posted: 9/13/2016 

blodg - You will not see water squirting out on suction side leaks. Any leaks before the pump will we suction leaks which such air into the system. To identify these leaks, apply a soapy solution around any connection on the suction side of the pump and watch for soap bubbles being sucked into the leak. If your pump cover o-ring is old, I would replace that first.
 Reply

 Posted: 9/12/2016 

Earlier in the year, my filter would get air in it while the pump was running. I didn't understand it, because I didn't have a water leak. Since the pool chemistry was not being affected, I opted to wait to see if the problem progressed, and hopefully would identify the issue. Well, now the basket in front of the pump has air in it and will not pump out. I just re-greased the O-ring on that lid but nothing changed. The only thing that makes any sense is the seals in the pump as you described. But I still have no water leak!? Is that possible? I've replaced seals in pumps before, and it can be a real bear...I'd hate to do that if that can't be the problem. My pump is 20 years old and I've never replaced the seals on that pump. Thanks....great website and forum BTW.
 Reply

InyoPools Product Specialist  Posted: 9/10/2016 

DerfScherf - Put a soapy solution all around the diverter valve and see if any bubbles are sucked into a leak on the diverter. However, from your description of a water loss, it sounds like your problem may be with the skimmer. You may have a break in the skimmer or around base of the skimmer where it connects to the pipe. Turn your pump off and let the water setter for 10 minutes. Then put some food coloring in a straw, close the top of the straw with your finger, and place the end of the straw near the bottom of the skimmer. Then release the dye and see if it gets sucked into a leak at the skimmer connector.
 Reply

 Posted: 9/7/2016 

I forgot to add that I am losing water (approx. 3"-4" / week) I had a similar problem with the cavitation issue a few years ago and was fixed by replacing the brass gate diverter valve. Is there a way to repair the line from the skimmer without busting up all the concrete?
 Reply

 Posted: 9/6/2016 

I have a in ground pool and I think I might have a air leak on my skimmer line to the pump. I have large brass diverter valves for the skimmer and the main drain lines to the pump. If I open the skimmer valve all the way open I get air bubbles and the pump cavitates. It will only work correctly if I only open the simmer diverter valve no more than 2 turns. How do I determine if there is a problem with the diverter valve or a leak in the line?
 Reply

InyoPools Product Specialist  Posted: 9/6/2016 

Jojo - I'll have to think more on this one. Normally, on the discharge side, a leak would show up as a squirt - water being pushed out of the hole, not air being sucked in. But, who can argue with success?
 Reply

InyoPools Product Specialist  Posted: 9/6/2016 

sch - How do you know that the filter is half full when it is closed and running? What is your filter pressure gauge reading? If it is high, you may have air pressure building up in the top of the tank due to suction air leaks. If it is low, and you may have low water flow, you may have a blockage in the system before the filter. A clogged impeller is a common issue. Also, the water in the filter will drain back into the pool when the filter is open. It can only fill up completely when the system is closed.
 Reply

 Posted: 9/3/2016 

I just wanted to add that a worn out gasket on your chorinator lid will cause air in your returns. This is on the return side so most would not think this as possible. I know it's true because I just fixed mine after spending most of the day running down possibilities on the intake side only!
 Reply

 Posted: 9/3/2016 

I have a Hayward pup and a Stay Clear C5025 filter. My problem is my filter is only half full of water when running. I can use the bleeder and it takes just as long as after I clean my filters to bleed the air out. 10 minutes after bleeding it is half empty again. I have a good prime and my leaf basket on the pump is full and stays full. I am getting yellow algae unless I run the pump 24 7. Sometimes when I fill the filter after cleaning it drains before I put the top on. Then if I try it again it stays full.
 Reply

InyoPools Product Specialist  Posted: 8/24/2016 

lh - Yes, close off your skimmer intake and pull your water from the main drain. And you could add water to the intake pipes through the pump strainer basket, but the pump should prime with some air in the intake pipe without damaging the pump.
 Reply

 Posted: 8/23/2016 

Hi,

Thanks for the info. I was away for a couple weeks and when I came back, the water level in the pool was very low, below the side skimmer. Adding more water is not an option right now because my water level in my well is pretty low. 2 questions:

1. While I'm waiting to have more available water to fill with, can I just switch the intake from partially side and partially bottom to only intake from the bottom of the pool?

2.Should I do something else before turning the pump back on if there is already air in there, or just let it stay on and the air will run through? Or will air running through damage the pump set-up?

Thanks for your help!

 Reply

InyoPools Product Specialist  Posted: 7/31/2016 

Evasport - The impeller in your Booster pump may be clogged. See our guide on "How To Clean Out a Pool Pump Impeller".
 Reply

InyoPools Product Specialist  Posted: 7/31/2016 

Big Bear - I do not understand your problem entirely. If you have some bubbles at the top of your pump strainer pot just under the cover, that's not uncommon. If you have significant bubbles, you have a leak somewhere in the suction line(s) between the pump and the pool. Try putting a soapy solution around the connections in the suction line(s).If you have a leak, you will see the soap bubbles moving around the point of the leak.
 Reply

 Posted: 7/29/2016 

I recently brought and installed a PB4 Booster pump for my inground pool.The motor works fine the shaft is turning, however I cannot get my Polaris pool cleaner to operate.Any suggestions. Also the Polaris does work. It seems that there is no pressure coming through the eye-inlet.
 Reply

 Posted: 7/28/2016 

Masaic air in pump, made all normal checks, (nothing), repiped run just drain no different, new pump nothing makes any difference.
 Reply

InyoPools Product Specialist  Posted: 7/19/2016 

Glynn - If you only see these bubbles on startup that's all right. If they are continuous and significant, you probably have a suction air leak in your pool system between the pool and the front on of the pump. This guide covers the location of the major sources of air leaks. Try placing a soapy solution on all the connection points around the pump and between the pump and the pool. You will see some motion in the soap bubbles as they are sucked into the leak. If you have a suction cleaner, remove it and see if that eliminates the air bubbles. If so, your problem is probably in the cleaner hose.
 Reply

 Posted: 7/17/2016 

My water pressure gage is perfect but I'm getting air bubbles through my water outlets in the pool why is this?
 Reply

InyoPools Product Specialist  Posted: 7/5/2016 

jimmac - Bugs in your system and low pressure may indicate partial blockages in your pump's impeller and filter. See our guide on "How To Clean Out a Pool Pump Impeller". Clean filter.
 Reply

 Posted: 7/2/2016 

I have air bubbles in the pop ups and low pressure in the returns and lots of bugs coming out of one of the returns? thank you
 Reply

InyoPools Product Specialist  Posted: 6/30/2016 

LeeAnn - From your description. it sounds like your leak in the pool liner. If the leak was in the pipes, you would not be losing that amount of water with the pump off.
 Reply

 Posted: 6/30/2016 

Inyopools, thanks for the response.
I have cartridge filters, and I did try running it without the filters in. Took the psi from 20 to 18, but nothing significant. I'll try your suggestion about running a plumber's snake down the skimmer line and see if that stops the bubbles.

 Reply

 Posted: 6/29/2016 

I have a BIG leak in our in-ground pool (about 4.5 inches per day) but there is no evidence anywhere in the yard. We have no idea where the water is going. The bigger problem is that we don't know where the leak is. We have tested loss with the pool running and with the pump off to see if that would help pinpoint it. We were told that if the loss was the same the leak would be in the pool and if the loss was more with the pump running it was in the pipes. The difference was only 5/16 of an inch which is not much considering the total loss! We have looked all over the pool liner and tested as best we can with dye and cannot see where the leak could be inside. I have to decide what to tell the leak detectors to do as the fees are different and separate for diving the pool and testing the pipes and both are expensive! What do you recommend? Any other tests I should try or advice for me? Which one do I do? HELP!
 Reply

InyoPools Product Specialist  Posted: 6/29/2016 

BlackhawksFan - If you have a sand or DE filter, try bypassing the filter in the recirculate mode. If the bubbles stop and the flow is good, it may be time to change the filter sand or DE. If you have a cartridge filter, try running the filter without the cartridge. If that solves the issue, you may have to replace the cartridge. Over to the skimmer. You may have a partial blockage in the first elbow after the skimmer. Try running a plumber's snake through that elbow. And lastly, as the pool ages and settles, it sometimes gets cracks around the skimmer. You will probably have to have someone else look at that.
 Reply

 Posted: 6/28/2016 

This year I started getting bubbles from the return jets and higher than normal psi at the filter (20 vs. 12-15 normally). When I turn the valve on the suction side and close the skimmer off, the bubbles stop. I've visually checked the skimmer housing and don't see any cracks, water level is good, and the flapper isn't stuck. I'm hoping it's not an underground issue. Anything else I can check?
 Reply

InyoPools Product Specialist  Posted: 6/28/2016 

MRC57 - Most pumps will have some minor air bubbles in the top of the strainer basket. Based on your psi and apparently good water flow, I would conclude that your system is running well. If you want to ensure that you have no suction air leaks, try smearing shaving cream around the strainer cover and pipe connections on the suction side of the pump. Any air leaks will show up as pot holes in the shaving cream.
 Reply

 Posted: 6/27/2016 

I have some noticeable air bubbles in my pump basket. My return line is working fine, with no air coming out. A friend of mine had mentioned that I should have no air bubbles in the pump basket. My pressure gauge in my sand filter is around 12-14 PSI which remembering from last year is pretty normal. I have no water leaks that I can see. Should I be worrying about the air bubbles in the basket? I checked all the o-rings and everything seems to be fine. The entire set up is only 1 year old. I haven't lubed any of the o-rings yet, not sure if that will make a difference? Any advice will be much appreciated.
 Reply

InyoPools Product Specialist  Posted: 6/26/2016 

Robert - Try wrapping the threads of the relief valve with plumber's tape for a better seal. Also, try using shaving cream instead of a soap solution to locate suction air leaks. The leaks will be more obvious.
 Reply

 Posted: 6/24/2016 

I definitely have an air leak but it's gotten worse in last few days. The main pump basket slowly drains (really slow but still drains overnight) when pump shuts off. I'll be doing a soap-test on lid, pipe unions, etc. I also suspect a tiny leak at the base of air relief valve. Should I be able to seal the valve base area or will I need a new relief valve? The gauge itself seems to be fine.
 Reply

InyoPools Product Specialist  Posted: 6/20/2016 

Fulk - I don't know what impeller backspin is. A pool motor can only spin one way by design. And where did the metal shavings from the threaded area of the impeller come from? Something wasn't working right on this new motor/impeller. And I would still spread shaving cream around the strainer lid to see exactly where the suction leak is and to show that it was not corrected by installing a new O-ring. This installer is not going to replace this motor. Get another pool man that will work with you.
 Reply

 Posted: 6/17/2016 

The pool guy came back out, took apart the motor and said the impeller backspun, cleaned outsome small metal shavings from the threaded area of the impeller where it goes on the shaft, put it all back together and turned it on. He absolutely will not submit for a new unit and swears the air leak is coming from the skimmer line even after i showed him the "dents" where the lid sits and told him about the hand soap getting sucket in under the lid making bubbles in the hair trap basket when i tested for a leak. Home warranty is giving us the run around along with this guy. He wants to put stop leak in the skimmer line.
 Reply

InyoPools Product Specialist  Posted: 6/17/2016 

Fulk - Sounds like you have a bad "new" motor. Hopefully, the pop and humming of the motor is only a failed capacitor. To see what's involved in replacing a capacitor, see our guide on "How To Replace a Pool Pump Capacitor". To verify leaks around the strainer cover, try spreading shaving cream around the edge of the cover. You will confirm better when the suction leaks are and whether or not you can fix them. From your description, you may have a damaged motor with dents around the cover seal that the O-ring won't seal. And you already know this, but you need a new pool repair man.
 Reply

 Posted: 6/16/2016 

So turned on the pump, heard a loud pop and now the "new" motor just hums.....
 Reply

 Posted: 6/16/2016 

Did a hand soap "test" around the strainer lid and am pretty sure this is where the suction leak is coming from. The soap was sucked in along the edge of the lid at several different places. I shut the pump off, opened the lid and had some suds inside the basket.....I also looked and felt around the edge and there are about 3 spots that look and feel like they are dented right where the O ring and lid make contact with it...
 Reply

 Posted: 6/15/2016 

Pool Service guy came out, would NEVER recommend his company to anyone, very undependable. Said the motor was bad but didn't check anything else. 3 days later he replaced it. Turned it on and decided to check the impeller and said it and the brass seal were bad as well. Had to order the impellor and seal but the "new" motor ran fine. After he replaced the motor every time we shut the pump off a "burp" of water would splash out from under the hair trap lid which it never did before. There is a new O ring on the lid also. It took the guy 2 more weeks to get the parts and come back out to put them in. He threw in a handful of granular chlorine, said it should help (water was shamrock green from algae) said he had other things to do and left. Took a total of a month just to get the motor and parts replaced. Everything worked great, had 20-25psi even while vacuuming and no bubbles for 2 DAYS! Now you can hear the "new" motor making a "pulsating" sound like the old one did, strong and then weak and the pressure is flucuating again between 0-15 and bubbles are horrible in the hair trap and return jets just like before! He did not check any of the plumbing to or from the pump for leaks. We are so frustrated and don't know what else to do. I imagine there is an air leak in the plumbing above ground somewhere but am confused about the pump issue. Is it possible its a bad pump or one with a hairline crack in the cast iron?......any suggestions?
 Reply

InyoPools Product Specialist  Posted: 6/14/2016 

Brad - You may have leaks in your cleaner hose or its connections. Hold the sections of hose that float on the top of the pool under water. If the stops loss of prime, you have a leak in one of those sections. Take one section out at a time to isolate the leaky section. If that doesn't work, check the section of hose that is going into the skimmer for leaks. If possible, submerge the hose below the water surface at the skimmer. Make sure the skimmer bucket is full of water so that air isn't getting into the system.
 Reply