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.

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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 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.

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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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(521 to 560 of 604)

InyoPools Product Specialist  Posted: 5/24/2013 

air through skimmer - Check for leaks around the bottom of the skimmer port and at the skimmer side of the diverter valve. If you find no leaks, you may have to have someone check your skimmer line.
 Reply

Anonymous  Posted: 5/23/2013 

We have an inground pool and it is blowing air out the outlet. It doesn't have air in the pump basket when the main valve is open but as soon as I open up the skimmer valve air starts pouring into the pump basket allowing air to blow thru the outlet. Any ideas we tried running a fish wire thru the skimmer pipe and doesn't seem to have any clogs.
 Reply

InyoPools Product Specialist  Posted: 5/4/2013 

BrianO - If you can correct your back pressure issue, even for a short time, by backwashing your filter, it sounds like an issue with your filter. It sounds like your sand is not being cleaned completely after a backwash. Sometimes pool chemicals or old debris get embedded in the sand and can't be cleared out. If you haven't changed your sand for a while, I would try that.
 Reply

 Posted: 5/4/2013 

I am having intermittent problems with back pressure, when I shut down my pool filter, water and air rushes back thru the pump and basket, oftentimes it blows the cleaner hose off the wall of the pool, I am completely baffled what may be causing this and what I should do to remedy the situation, there have been times when a good backwash seems to clear things up, then no issues for weeks then it comes back. Any thoughts out there? Thank you in advance - Brian
 Reply

InyoPools Product Specialist  Posted: 4/23/2013 

pit - The recirculation setting bypasses the filter, so it sounds like you have a filter issue. Try backwashing a couple of more times. Make sure you go through the rinse cycle to purge the loosened contaminates after backwash. See our guide on How To Backwash a Pool Sand Filter. If that doesn't work, it may be time to replace the sand or DE material.
 Reply

 Posted: 4/22/2013 

i have a pool after back washes i turn on filter runs for 30 minutes and slows down put on recirculate run all the time
 Reply

InyoPools Product Specialist  Posted: 4/19/2013 

FrankCCC - Sounds like the same issue addressed in the last comment - a pressure back up problem in the return side of the pump. Pump is trying to push more water to the pool than the return lines can handle. You may have a clog in one of the return lines. Or if you have diverter valves after the filter that shut off some of the return lines partially, open them up. And as a last resort, try replacing the return jets with ones with larger diameters.
 Reply

InyoPools Product Specialist  Posted: 4/19/2013 

back pressure - You state that when you turn off the pump, water gets sucked back to the pool. This sounds like a water pressure issue which happens after the pump. Suction issues (air leaks) are between the pool and the pump. Something is causing a buildup of water pressure in the return lines after the pump. The pump is trying to push more water back to the pool than the return lines can handle. This causes a pressure build up in the filter. When the system pump is turned off, that pressure causes the water to reverse back through the pump and input lines from the pool. One filter rep has suggested replacing the return jets with larger diameter jets to relieve this pressure.
 Reply

 Posted: 4/18/2013 

I have the same problem as the post below from Brian back on 9/19/12. Checked and replaced all O-rings around filter and pump and replaced all 8 cartridges in my Filter. Filter baskets looks fine, water level at top and I see no bubbles returning to pool but if filter runs for more than 2 hours and I shut it off the back pressure sucks all water out of the Filter baskets towards pool and even blows the lid of the pool deck strainer cover, pressure is fine on the filter 20 which is normal for my system when clean. Any suggestions or help would be appreciated
Thanks Frank

 Reply

Anonymous  Posted: 4/17/2013 

We have had air bubbles coming from the jets in our pool. We have replaced the pump, replaced the underground flexible pipe for rigid pipe so no problems there. We have checked as many o-rings and union connections as we can but still there is air in the system and it is quite a lot of air. When we switch off the circulation the water in the sand filter seems to get sucked back and the glass lid at the top is full of air. Also the pump filter basket has a lot of air in it. The dial you turn for different system operations appears to be leaking a little water. Could this be the problem? Please can you suggest anything to solve this. Many thanks.
 Reply

InyoPools Product Specialist  Posted: 4/15/2013 

BRUNO - According to the Spa expect, you may have blockage in the face of the jets that disrupts the blending of air and water through your jet lines. Check for clogs at the jet face. If you have roto jets that aren't moving, they should be replaced.
 Reply

 Posted: 4/12/2013 

I HAVE BUBBLES COMING OUT OF ONE OF THE JETS IN THE SPA HOW CAN I FIX IT.
 Reply

 Posted: 4/12/2013 

Jeff. I cleaned the basket near the filter . It was plugged solid, the new kid that cleaned the pool yesterday must have neglected that. The bubbles stopped almost immediatly and a full flow is now working. Thank you , I will retain your instructions Ray
 Reply

InyoPools Product Specialist  Posted: 12/30/2012 

Mike - Can you give us a call at 877 372-6038 x717. It's not clear how you are set up. Is the cleaner connected to a dedicated suction line or is it going to the skimmer?
 Reply

 Posted: 12/25/2012 

I have replaced pool pump hoping that will solve my problem as soon I connect pool cleaner start sucking air and stops working, new cleaner and I have try different set of hoses. I have dug up all the way to the skimmer box hopping to find some leaks. no idea what to do next other then blowing up pool,any one come across something like that please help.
 Reply

 Posted: 12/8/2012 

Thank you for the advise, had a problem and thought money money but thanks to your web sight found the problem and fixed it so easy thanks again have a great day Alb
 Reply

InyoPools Product Specialist  Posted: 10/28/2012 

Sean - You may not have enough suction to operate your cleaner. Try shutting down the other suction ports like the main drain and the skimmer so that most of the suction is coming from the dedicated suction line to your cleaner.
 Reply

 Posted: 10/27/2012 

Hello,
I am having some trouble with my pool, the system runs fine until i connect the Genie Barracuda cleaner and this will run for about a minute and then it seems to lose suction and the pump seems to be straining. I have replaced all the hoses and also the pump seals and have checked for any debris in the impeller but i still am having this issue. Any ideas on what step i need to take next?

Regards
Sean

 Reply

InyoPools Product Specialist  Posted: 10/9/2012 

silver1935 - If the INK is being sucked back right after you turn off the pump, it may be a pressure adjustment in the system. If the INK suck back occurs after the pump has been shut off and every time you put new INK in, you may indeed have a pipe leak.
 Reply

 Posted: 10/8/2012 

I have a leak in a 16x32 inground pool.
Have being trying to find for some time & have notice
when using INK that one of the return lines does suck in the ink with the pool not running.
Does this mean that I have leak in the line.
Tks

 Reply

 Posted: 9/19/2012 

I had a problem recently where when my pool pump shut off, I got a big back surge of pressure that actually blew the skimmer covers off. I researched on the Internet and indications were that I have an air leak somewhere in the system, that causes pressure to build in the sand filter. Consequently when the pump is switched off I get the back surge and the prime in the pump filter basket is lost. I have been switching the pump on and off since then to manage the problem.

I ran the system on recirculation only for a few hours and could see bubbles coming from the jets, but when I switched off there was no back surge.

I have replaced the filter pump cover seal, noticed a small leak on the connection to the top of the pump (outlet that goes to the multi-valve housing) so replaced the seal and lubricated the new seal.

I cannot see any leaks on the joints to the sand filter, but have not taken them apart. They appear dry however and don't look they are leaking. My pressure gauge is reading normal, but I am concerned it is not working properly as I would expect to see an increase over time. I have done a backwash to be on the safe side.

I have run out of ideas now, the system seems to run at a very good pressure and after 4 years of running there was always a little bit of air under the pump filter cover which never seemed to be a problem before, but now I have the back surge problem and can't seem to resolve it. Been going on a couple of weeks now. Any suggestions would be greatly appreciated.

 Reply

InyoPools Product Specialist  Posted: 9/1/2012 

Steve - If your pump is maintaining prime and you are only seeing air coming from one return port, I would think you have a leak in the one return line in the piping going to that return port. Animals sometimes dig under the pool and get into the piping. I'd appreciate your sending back a note if you resolve this problem.
 Reply

 Posted: 8/31/2012 

I just recently started to notice a significant amount of aire bubbles and noise from only one of the two return lines. I am going to replace the pump cover gasket, union gasket, re-dope the pump drains to see if this helps. Is this sign of bubbles coming out of one return a sign of a possible leak somewhere underground?
 Reply

InyoPools Product Specialist  Posted: 8/30/2012 

Kristy - Try backwashing your filter a couple of times. If that doesn't improve water flow you may have a block in your line after the filter. If you are losing prime in your pump, you have a suction leak on the pool side of your pump.
 Reply

 Posted: 8/28/2012 

I have a sand filter system for my above ground pool and we have recently run into a problem. When we first got it everything was great but recently the water return isn't as strong as it started off the beginning of the summer. The suction is good but the return is weak, so of course the water isn't being circulated like it should. What would you reccomend for this problem
 Reply

InyoPools Product Specialist  Posted: 8/15/2012 

Jeremy - If you only have occasional or small bubbles coming out your returns, I would not worry as long as your pump is maintaining prime.
 Reply

 Posted: 8/15/2012 

Can you quantify "significant air bubbles" a little better?

My pool always primes quickly, but tends to have "some" bubbles. I see only very small bubbles sneaking out of the spa returns but 1 of the pool returns gets larger bubbles at a consistent pace.

How much bubbling is considered normal or not a cause for concern?

Thanks for the great guide, I would just like to know if what I consider a small amount of bubbles is worth calling in a pro to do a pressure test.

 Reply

 Posted: 8/3/2012 

I have bubbles coming out of one pool jet, when the pump is on low (I have a new inground pool, with a Haywood two speed salt system. The pool builder first said the water was to low, so I added water. The bubbles are still there on low, but not high. The pool builder then said the bubbles were normal on a two speed system and that his pool did the same thing on low speed. My question is this normal. I think it may just be because the builder does not want to pay for any repaires.
 Reply

InyoPools Product Specialist  Posted: 7/22/2012 

murphy's law - Consistent air bubbles out the return ports and in the strainer basket is usually a sign of a leak on the suction side of your pump. Check the strainer cover gasket, the O-rings in any unions going into the pump, and the diffuser gasket. If you had to cut out the old pump, check that the glue sealed the new fittings all around the pipe.
 Reply

 Posted: 7/21/2012 

We have a fiberglass San Juan Pool. It is about 7 yrs old. We put a new pump in last year. This year we noticed water coming out of the jets with small bubbles with lots of force and the strainer also has lots of bubbles.Our pressure shows about 7 Just wondering where to start.
 Reply

Anonymous  Posted: 7/9/2012 

I have a Hayward sand filter (using with gravel instead of sand) powered with a 1 and a half horse power pump that I am using for my koi pond. I have a problem with the flow slowing to hardly anything after about 30 minutes with the pump running on low speed. The pressure never reads higher than 3 lbs. My water is clear, no algae, I backwash frequently, the flow is fine for a short time and then the flow slows to a trickle. If I turn the pump off and then back on, the flow comes back pretty much to normal. Somehow there is air getting into the filter, but I am stumped as to how and where. There is no visible air in leaf basket dome. When I open air valve on low speed no air comes out, but when run on high air does come out. I am stumped. Please offer any advice.
Thanks so much.

 Reply

InyoPools Product Specialist  Posted: 7/3/2012 

RD - If you have water spraying out of the top of the strainer basket when you shut off the pump, that means the pump is sucking air through that hole when the pump is running and you will lose pressure. I would replace the o-ring under the cover with a new one.
 Reply

 Posted: 7/1/2012 

I have a lot of bubbles rising to the surface from both return jets. The force of water coming out is pretty good despite the air bubbles. In trying to troubleshoot I noted a small bit of water shoot out the pool pump strainer lid when I turned off the filter/motor (it did seem sufficiently tight when I subsequently loosed the screws). A few weeks back I had found a O gasket in the strainer basket and set it aside not knowing its origin. I'm wondering now if it belongs in the intake side of the pump motor (after strainer basket) as it seems to fit; although I was hesitent to place it in without being 100% sure. Any advice is greatly appreciated (I have a Magenetek Centurian switchless motor - B638). Thannks
 Reply

Anonymous  Posted: 6/27/2012 

I have air coming sporadically out of my jets. I also seem to be losing about a half inch to an inch of water a day.(It has however, been 100 degrees and very windy). When I turn my pump off, there is a tremendous amount of air released from the floor drain and water is forced from the pump at the debris basket. When I turn the pump back on, sometimes I have to add water several times to get the pump to prime, other times when I unscrew the pump basket lid it backfills on it's own. While the pump is running there is air visible in the pump basket area. The motor is new about 6 weeks ago, this problem started about 3 days ago. Now my pool is getting cloudy...I hope someone has some words of wisdom! Thanks!
 Reply

InyoPools Product Specialist  Posted: 6/26/2012 

karney - Adding a lot of chemicals to your pool can sometimes create foam - especially algaecide. To reduce this foam, try pointing your return jets down for a while and add a no-chlor shock treatment.
 Reply

 Posted: 6/22/2012 

I just installed a new water way system 2 hp pump 19 inch 1590 lb sand filter. I am having a lot of foam and even when I try to raise the water level it is coming out the back wash tube the foam, therefore loosing water. I have no leaks have checked again and again. There is a tube that has like a air outlet on the return to pool fitting on the new filter. I have added a LOT of chemical as I had not run my pool for 4 years. Any suggestions?
 Reply

Anonymous  Posted: 6/13/2012 

A "whirlpool" at the skimmer or vac cleaner port indicates that the pool water lever is too low...just add water!
 Reply

 Posted: 6/5/2012 

Having the same problem as Pat posted on 6/4/12. Lots of air at start up but once air clears runs fine no bubbles. We did have one day that the pump would not prime when we opened the basket no water running through. Now afraid to have pumps on timer to start up when we are not there to watch it.
Any sugestions?

 Reply

InyoPools Product Specialist  Posted: 6/5/2012 

Pat - It is not uncommon for some air to get into the system when the pump is shut down. On startup, you will see air initially in the basket chamber and coming out the ports as the pump is purging this air.
 Reply

 Posted: 6/4/2012 

I also seem to have an air leak. My problem is different though. The only time air seems to be getting into the system is when the pump is not running. A lot of air is discharged into the pool upon start up. No air bubbles are showing up anywhere, when the pump is running!
I'm at a loss. Can you help me?
Thanks...

 Reply