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.

Click Here to View Replacement Pump Parts 
 

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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(201 to 240 of 604)

InyoPools Product Specialist  Posted: 6/28/2017 

Darrell - It sounds like you have a suction air leak that is causing air to build up in the top of the filter tank. When you press down on the MPV handle, you are opening up the system and letting this air release. Suction air leaks occur in the connections at or before the pump on the suction side of the pump between the pump and the pool. Since the MPV is on the discharge side of the pump, any leak there would show up as a squirt. So concentrate on the suction side of the pump to isolate any suction leaks. Try covering suction side connection with a soapy solution. If it has a leak, you will see soap bubbles being sucked into the hole.
 Reply

InyoPools Product Specialist  Posted: 6/27/2017 

drigs - Your problem sounds the same as "not a problem solver" below. See my comment to him.
 Reply

InyoPools Product Specialist  Posted: 6/27/2017 

not a problem solver - If you have to bleed out air from the top of your filter to increase flow, you are definitely getting air into your system from suction air leaks and this is probably causing backpressure that's impeding water flow as it builds up. Many filters have a breather tube down the center of the tank to relieve this pressure. If you have one, check to make sure it and the screen filter at the top end of it are not clogged. The suction air leaks occur at connections between the pool and the front end of the pump. If you can't see anything with a soapy solution, try using something heavier like shaving cream. A suction leak will suck the cream in leaving a pothole.
 Reply

InyoPools Product Specialist  Posted: 6/27/2017 

Nidhu - Since your problems seemed to start when you opened up the strainer basket to clean out debris, I would start there. Look at the strainer cover O-ring. If it is old, stretched or damaged, it may not be sealing properly. I would replace it. As for your basket overflowing, when you open up the system, water will tend to move around to find its natural level. Also, if part of your problem is low water pressure, see our guide on "How to Correct Low Water Pressure in Your Pool System". See Step 6, Clogged Impeller, in particular.
 Reply

 Posted: 6/26/2017 

The flow out of my returns is low but the pressure is always the same as when I start it after a backwash. I cleaned the filter again today started it up and everything was fine for about an hour then the flow went down again. If I set the filter to recirculate the flow is normal. When I put it back to filter it will stay normal for about an hour again. I have a Hayward DE filter. The equipment is about 12 years old.
 Reply

 Posted: 6/26/2017 

This is our 2nd year with a pool. Older pool (30 years?). First summer, no issues. Noticed late summer that the pump was not getting great suction and flow into filter was slow. Someone finally told me to clean the cartridges . did so and everything was fine. Ran through the winter (Vegas, never froze) no issues.

About a month ago, replaced all 4 cartridges in Hayward filter. flow was great for about a day, then slowed. Then crawled, then seemingly nothing after a few weeks. Took them out and cleaned them ... same process.
This weekend cleaned them again (2 cleanings in one month!) and replaced the O-rings on the filter and on the filter lid. It is already back to seemingly no flow.

There is so little flow. I can bleed out air from the filter for about 20 seconds every day .. .it just comes back.

I have run a hose to test the flow to the holes in the pool, seems fine.
Same from the pump to the skimmer, fine.

Very few bubbles of air visible in pump basket window.

No visible water leaks in any of the exposed pipes. Have used the soapy solution, nothing that I can find.

Pump when it was working well made a noise, now it is whisper quiet.

I just want stuff to work .. that is all.

 Reply

 Posted: 6/26/2017 

Hi,
I have a DE filter.I see water coming out of filter basket when pump is turned off. I have two jets in the pool. One isn't doing anything and the one is majorly throwing air bubbles in the pool. This started happening after I back washed the filter and opened up the pool filter basket to take debris out. We are not really sure if this is normal for the pump basket overflowing with water when pump is off. Please advise.

 Reply

 Posted: 6/25/2017 

I have an issue with air in my pump. I ran a separate line from the pool directly to the pump to check if there was an issue with my underground lines- Same result. I have tried backwashing-same result. When I press down on the filter valve to relieve pressure , the pump pushes out the air and the chamber fills with water. When the filter handle is returned to normal , the air comes back. It sounds like the filter valve control is sucking air. its about 15 yrs old so maybe the seals are gone.
My heater keeps getting a low flow signal . Any thoughts?

 Reply

InyoPools Product Specialist  Posted: 6/20/2017 

tig - Thank you very much for your observation. The Teflon tape comment has come up before and we are trying to pull it out of our guides.
 Reply

 Posted: 6/20/2017 

I just want to note that in step 6, you shouldn't put teflon tape on the threads of the union. The O-ring provides the water sealing. Teflon tape will only inhibit the ability to get the ring properly tightened. Also, there are mixed opinions on using teflon tape on PVC in general.
 Reply

 Posted: 6/18/2017 

I researched this site and did a methodical, diligent step-by-step inspection of the whole routine (I'm a new pool owner with no experience; er....I'm new to pools). I found out that I had not opened one of the pipes on the suction side after backwashing. There was no reason for me to have closed it in the first place. I was just "checking systems" (ahem). The pump is fine. the water is now circulating and I have a huge job in getting the muddy Amazonian pond to look half-way respectable. I'm working on it through the stormy weather. I noticed that one the three water inlet into the pool is blowing a whole lot of air. I'm getting to that part now. Probably the gasket. Thank you.
 Reply

InyoPools Product Specialist  Posted: 6/17/2017 

Nashvillepool - When you say skimmer, I think you mean the strainer basket in the pump. If so, the only thing that could generate that much heat is the motor in the pump. If that is the case, I'm surprised that the motor didn't shut off before generating that much heat and I'm also surprised that all the pump's gaskets and the shaft seal weren't destroyed. With that much heat being generated, it sounds like you need a new motor.
 Reply

 Posted: 6/14/2017 

I have a Hayward Vari-Flo XL sand filter and a Centurion switchless pump. One day recently I noticed no flow to the pool. The motor was humming and the skimmer basket was warped (melted) form the hot water. (I replaced the basket) I turned the pump off and on again a few times and I can hear a faint hiss of air a few times. I checked to see if anything was lose. I backwashed and rinsed the filter once. Then, I turned the pump on again overnight. The pumps seems to be running and I can feel the pipes vibrating/humming (as if water was running). The water is not flowing into the pool though. I kept it on though and next morning, I found the water in the skimmer hot again. I turned everything off again. What should I be looking at? Is my pump shot or am I missing something fundamanetal? Thank you!
 Reply

InyoPools Product Specialist  Posted: 6/12/2017 

MickeyGzzz - If you mean the piece of short pipe that screws into the pumps discharge port, it could be an adapter or a union depending on how your intend to attach the filter.
 Reply

InyoPools Product Specialist  Posted: 6/12/2017 

mike - You may have an air leak in your cleaner hose. Try taking all but one or two of the hoses off and see if that correct your problem. If so, you need to buy new hoses sections.
 Reply

 Posted: 6/11/2017 

Please if someone can tell me what the pipe that screws into the discharge side port is ? I don't know what it's name is
So thank you

 Reply

 Posted: 6/10/2017 

I recently replaced my pump and it appears to be working fine and until i plug the pool vacuum hose into the skimmer. With the vac attached the pump begins to surge and suction is greatly reduced. The water level in the strainer drops to the level where the inlet pipe is connected. It acts like the vac hose is restricted but it isn't clogged or collapsing. Does this sound like an air leak?
 Reply

InyoPools Product Specialist  Posted: 6/9/2017 

Thawk654 - Check that your pump's GPM water flow is smaller than your filter's capacity. Your pump may be too strong for your filter. Make sure you have the right O-ring for your MPV. As you are tightening the clamp, hit it gently with a rubber hammer around its circumference to make sure it seats properly. Check that the clamp is not bent or broken.
 Reply

InyoPools Product Specialist  Posted: 6/8/2017 

DBoh - It sounds like you know the difference between a full rated and uprated pump, but check again that you don't have the impeller for a 1.5 full rated pump. A full rated propeller would require your 1.5 HP pump do the work of a 2 or 2.25 HP pump and it would fail. Assuming you have the right impeller, the whining is usually an indication that the bearings are going.
 Reply

 Posted: 6/7/2017 

Pressure showing 32-34psi.
Replaced the spider gasket as it was dripping water from backwash outlet.
Several days later, water started coming out of where the o-ring is. Removed multiport and replaced the o-ring with Lube Tube.
Pressure still at 32-34 and over a few hours, water begins shooting out of the clamp again.
The o-ring is "smashing" out of multiport.
I can sfigure out why this is occurring.

 Reply

InyoPools Product Specialist  Posted: 6/7/2017 

davidtfull - Thank you for your response. I would be very interested in your results to resolve this issue.
 Reply

 Posted: 6/6/2017 

Inyopools: I do not have a salt generator or a heater. Using chlorine tablets through an inline feeder. I ran a bead of silicone around all the pvc fittings on the suction side which eliminated the small bubble (about the size of a nickel) I had in the basket. The tiny bubbles in the pool are not affecting anything, just annoying is all. Will see if sealing the pvc joints has any effect and will report back if it does. I do appreciate your prompt response to my initial concerns. Thank you.
 Reply

InyoPools Product Specialist  Posted: 6/6/2017 

davidtfull - Not sure what this is but it doesn't sound like these bubbles are causing any problems. If you have a Salt Chlorine Generator, it produces very, very small bubbles at the exit end of the SCG that go out through the returns.
 Reply

 Posted: 6/6/2017 

For my pool we use a Hayward SP2607x10 pump with an uprated 1.5HP with the proper impeller upgrade kit. For the spring opening I took a sample to the pool store and bought the recommended products. I performed the regimen as instructed (as I done plenty times now) and suddenly at the end of day 3 the pump began to whine. I pulled everything apart and the were some soft pine cone sprouts in the impeller so I cleaned and reassembled. The pump still whines but the jets seem to push as hard as before and the skimmer "seems" to vacuum okay but the pressure is much higher than normal. Any ideas? I've backwashed etc. but there at time does seem to be air in the pump. Want to verify the impeller/pump is is the issue before spending $400 for a new pump


 Reply

 Posted: 6/6/2017 

I checked everything on the suction side and found no leaks. I have a very small air bubble in the strainer basket. but no bubbles coming out of the returns. Pump pressure holds steady at 15, pump holds prime, water pressure at the returns are normal, water level is correct but I still have very, very tiny air bubbles in the pool water. Very noticeable when the pool light is on. You can see tons of very tiny bubbles flowing in front of the light. When you stick your hand in the water the bubbles collect on the hair of your arms. Bubbles still remain even when the pump is turned off. What am I missing here?
 Reply

 Posted: 6/6/2017 

I've noticed after I backwash and return to filter mode, large amounts of air are in my return jets. Filter basket has little to no air. When pump turns off, the pressure pushes off the vacuum line and the water drains from pump. I then have to add water to filter basket in order to get it to prime. After several days, the air seems to flush from the system. But then I backwash again and the problem starts over.

It seems air is getting into the filter when I backwash - is this possible? If so, how do I prevent it?

 Reply

InyoPools Product Specialist  Posted: 6/2/2017 

Bob B. - The easy fixes first. Make sure your weir door is operating smoothly. Then check for a blockage in the first elbow of your skimmer using a plumber's line. If there is a blockage like a small toy that is jammed in, try opening up the diverter valve (main/skimmer and blowing the toy back to the skimmer using a Drain King attached to a garden hose. If the line is clear, you may have a broken joint where the skimmer attaches to the pipe and you may have to replace the skimmer (not easy).
 Reply

 Posted: 6/1/2017 

When running pool from port 1 (skimmer to filter) there is very little suction and a lot of air in the filter basket. When pool is running on port 2 (bottom of pool), it runs perfect. I have not noticed a lower water level although we have had a lot of rain. I'm assuming there is a crack or leak in the plumbing line. Any assistance would be greatly appreciated.
 Reply

InyoPools Product Specialist  Posted: 5/31/2017 

wspwithe - First, try putting only 80% of a full load of DE Powder when you recharge your filter. After a backwash, 20% of the powder is left in the filter. Second, if you have an air relief tube in the center of your filter, make sure it and the screen at the top of it are not clogged. Third, does this problem occur when you have the MPV in “recirculate’ mode effectively bypassing the filter. If so, your filter is not the issue.
 Reply

 Posted: 5/29/2017 

Our pool pressure has been running at 35 psi. Can't find problem. We cleaned and back washed DE filter. Turn it on, it runs at 20psi... we added DE powder...psi slowly rises...finally after about 1 hour water completely stops flowing from waterfall as if we turned it off. Definitely not filtering. Pool is green. We did remove the filter completely as well and clean it. At a loss.
 Reply

InyoPools Product Specialist  Posted: 5/23/2017 

Anonymous (AG air leaks) - There aren't many places for suction leaks between the pump and the pool, generally only the two fittings at the pool and at the pump. If these are unions, check the placement of the O-rings in the unions and tighten the unions up. If these fittings can’t be removed easily, try sealing the connections with silicon glue.
 Reply

Anonymous  Posted: 5/22/2017 

Do you help with Above ground pool air leaks? We have actual foam that appeared on top of the pool after we opened the pool. We finally figured it out that it is due to an air leak from some where....no visible leak. Can you guide us?
 Reply

InyoPools Product Specialist  Posted: 5/22/2017 

islander - I don't know why the multiport valve Filter position would cause air in the pump's strainer basket. The water in the filter's multiport valve has passed the pump and shouldn't impact the pump’s operation. It shouldn't matter, but check the spider gasket in the MPV for damage. Then review this guide again for identifying air leaks.
 Reply

 Posted: 5/20/2017 

When my sand filter is set to "Filter," bubbles exit the returns and air gradually accumulates under the strainer cover. Eventually, the pump no longer takes in water. When I set the filter to "Waste," the air under the strainer cover gradually decreases and the pump functions normally. So...not a suction problem, I suppose. Ideas?
 Reply

InyoPools Product Specialist  Posted: 5/19/2017 

Ray - See our guide on "How to Correct Low Water Pressure in Your Pool System". A clogged impeller (Step 6) is a common problem.
 Reply

InyoPools Product Specialist  Posted: 5/19/2017 

DD - You may have several problems. For DE powder in the pool see our guide on "How To Prevent DE Filter Powder Returning to Pool". For low water flow, see our guide on "How to Correct Low Water Pressure in Your Pool System". A clogged impeller (Step 6) is very common. For air in the return lines when vacuuming, you may have a leak in the vacuuming hose. Try holding the entire hose under water to see if the air bubbles stop. If so, you have a leak in the hose. Take a section of the hose out one at a time to isolate the leak.
 Reply

 Posted: 5/18/2017 

I'm having problem building pressure (only got about 2 psi) Normally pool runs around 10 psi. I do have some bubbles sputtering from one of my return jets. I had to replace the spider gasket in my Hayward Vari Flow valve as that was broken. I thought this may have been the problem but it did correct it. I have also replaced the pressure gauge. Any suggestions on where to go to next?
 Reply

 Posted: 5/17/2017 

Hello, Thank you for all this helpful information. I had DE powder go back into the pool, have air coming from return lines when vacuuming, and I don't seem to have good suction from the skimmer. Are these things related?
 Reply

InyoPools Product Specialist  Posted: 5/17/2017 

Cmoctezu - See our guide on "How to Correct Low Water Pressure in Your Pool System". A clogged impeller is one of the most frequent low-pressure problems.
 Reply

 Posted: 5/16/2017 

The gauge is reading 15 psi, but the water pressure feels weak compared to how it normally runs. I checked everything, clean the filter, etc., and she I first turn it on the pressure is fine, but after a bit it is weak again. However the gauge is always at 15 psi, unless it's shut off.
 Reply