How to Identify and Correct Air Leaks

WRITTEN BY:  Inyo Pools

  3.82 out of 5 stars on 17 ratings
(Click on a star to add your rating)

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

Top

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.

Step 2

Go over to the pool and check the water level. Ideally the pool water level should be at least halfway up the skimmer intake. If the water level is below this level, the skimmer is probably sucking air into the skimmer pipe to the pump. This is a simple problem to resolve. Simply fill the pool to the halfway point of the skimmer. Also check that nothing is holding up the flap of the skimmer opening to the pool. This could also let air into the skimmer suction pipe.

Step 3

If the pool water level is adequate, your next step is to check the strainer lid on the pump. If it is not on tightly, you may be sucking in air around the lid. To check the lid, first TURN OFF THE POWER TO THE PUMP at the breaker box.

Step 4

Remove the pool pump strainer lid. These are generally screwed on or are secured with toggle bolts. Pull the O-ring out of its groove. Clean out any debris that might be in the groove. Check the O-ring for any cracks or wear. Sometimes an older O-ring is stretched so that it bulges when you try to replace it in its groove. This is a common source of leaks. When you screw on the lid, the O-ring will bulge out and create a leak. Replace a worn or stretched O-ring. Also, it's a good practice to lubricate the O-ring lightly before replacing the lid. Use a good pool seal lubricant (Teflon or silicon). DO NOT use petroleum jelly.

Step 5

If your pool pump strainer lid was not the problem, check the union commonly inserted before the pump. Again make sure that the power to the pool pump is turned off before unscrewing the union.

Step 6

After separating the union, you should see an O-ring in the groove of the union. As mentioned in Step 4, check that this O-ring is not worn or cracked and that it is seated correctly in a clean groove. Lubricate the O-ring. Retape the threads of the union with two or three layers of Teflon tape and reconnect the union. Tighten the union by hand.

Step 7

If these steps have not corrected your air bubbles, and you have an older pool pump, you may have a leak in the motor shaft seal. The picture (left) shows the location of the motor shaft seal in a cutaway version of a Hayward pump. For instructions on replacing a motor shaft seal go to our guide, How To Replace A Motor Shaft Seal.

Step 8

Another source of air leaks is the motor's drain plug on the suction side of the motor. If this plug is loose, tighten it to stop the leak.

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

Top
(1 to 40 of 321)

Inyopools  Posted: 09/16/2016 12:18 PM  Inyo Product Specialist

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.


blodg  Posted: 09/15/2016 15:07 PM 

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?


Inyopools  Posted: 09/13/2016 22:48 PM  Inyo Product Specialist

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.


blodg  Posted: 09/12/2016 9:10 AM 

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.


Inyopools  Posted: 09/10/2016 16:53 PM  Inyo Product Specialist

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.


DerfScherf  Posted: 09/07/2016 19:09 PM 

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?


DerfScherf  Posted: 09/06/2016 15:59 PM 

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?


Inyopools  Posted: 09/06/2016 9:53 AM  Inyo Product Specialist

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?


Inyopools  Posted: 09/06/2016 9:44 AM  Inyo Product Specialist

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.


Jojo  Posted: 09/03/2016 20:42 PM 

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!


sch  Posted: 09/03/2016 19:43 PM 

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.


Inyopools  Posted: 08/24/2016 9:36 AM  Inyo Product Specialist

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.


lh  Posted: 08/23/2016 18:49 PM 

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!


Inyopools  Posted: 07/31/2016 23:42 PM  Inyo Product Specialist

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


Inyopools  Posted: 07/31/2016 13:07 PM  Inyo Product Specialist

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.


Evasport  Posted: 07/29/2016 21:13 PM 

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.


Big Bear  Posted: 07/28/2016 20:43 PM 

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


Inyopools  Posted: 07/19/2016 18:46 PM  Inyo Product Specialist

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.


Glynn  Posted: 07/17/2016 13:22 PM 

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


Inyopools  Posted: 07/05/2016 12:39 PM  Inyo Product Specialist

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.


jimmac  Posted: 07/02/2016 13:16 PM 

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


Inyopools  Posted: 06/30/2016 18:30 PM  Inyo Product Specialist

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.


BlackhawksFan  Posted: 06/30/2016 9:26 AM 

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.


LeeAnn  Posted: 06/29/2016 17:20 PM 

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!


Inyopools  Posted: 06/29/2016 10:30 AM  Inyo Product Specialist

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.


BlackhawksFan  Posted: 06/28/2016 17:34 PM 

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?


Inyopools  Posted: 06/28/2016 11:39 AM  Inyo Product Specialist

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.


MRC57  Posted: 06/27/2016 8:42 AM 

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.


Inyopools  Posted: 06/26/2016 13:19 PM  Inyo Product Specialist

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.


Robert  Posted: 06/24/2016 17:58 PM 

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.


Inyopools  Posted: 06/20/2016 11:38 AM  Inyo Product Specialist

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.


Fulk  Posted: 06/17/2016 12:34 PM 

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.


Inyopools  Posted: 06/17/2016 1:05 AM  Inyo Product Specialist

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.


Fulk  Posted: 06/16/2016 21:24 PM 

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


FULK  Posted: 06/16/2016 5:33 AM 

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...


Fulk  Posted: 06/15/2016 1:55 AM 

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?


Inyopools  Posted: 06/14/2016 11:38 AM  Inyo Product Specialist

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.


Inyopools  Posted: 06/13/2016 23:34 PM  Inyo Product Specialist

Nick - See our guide on "How To Prevent DE Filter Powder Returning to Pool" for possible causes and solutions of DE going into the pool.


Inyopools  Posted: 06/13/2016 13:01 PM  Inyo Product Specialist

mpives58 - You still may be getting air sucked into your system on the suction side of your pump. A couple of thoughts. Did the tradesmen work near any of the underground suction pipes (assuming you have an in-ground pool)? Could they have loosened one of the joints? Thought two. Do you still have bubbles, if your run without the cleaner vacuum plate installed - e.g. without using the cleaner? If not, you may have a leak in one of the cleaner hoses or the plate. Is the plate completely under water? To test for a leaking hose, try holding all the hoses under water when the cleaner is operating.


Brad  Posted: 06/12/2016 16:45 PM 

Great site guys! I have a Pentair diverter to allow my inground pool to filer via the skimmer or the drain or both. When it is filtering via the drain, skimmer or both there are no issues. Only when I attempt to vacuum via the skimmer air is introduced into the pump and I loose suction. Any suggestions?