How to Identify and Correct Air Leaks

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If you are seeing a significant number of bubbles coming out of your return lines into the pool, you probably have an air leak in your filtration system. Possible sources of this problem are low pool water levels, leaks around the strainer lid, leaks in the unions or leaks in the pump seals. For optimum pool pump operation, the source of the leak must be identified and corrected.

Video

Step by Step

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Step 1

Your swimming pool filtration system has two sections: the suction side (from the pool to the pump) and the discharge side (from the pump to the pool). Check the strainer pot of your pump. If you see a significant number of air bubbles moving through the strainer pot, you know that the air leak is somewhere on the suction side of the system plumbing before or at the pump.

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Step 2

The ideal water level should be at least halfway up the skimmer intake. If the water level drops below that level, the skimmer can start to gulp air with the ebb and flow of circulating water.

This simple problem has a simple fix: add water. Drop in a hose, and get that water level up. Keep an eye on it in the future to prevent a reoccurrence. A simple add-on feature is water levelers, that make sure your water is always at optimal levels.

Step 3

Before we begin the actual inspection of the plumbing elements. Switch off the master breaker to your pool pump.

Release water pressure in the system using the air relief valve on your filter. The air relief is generally only found on Cartridge and De filters. Sand filters do not have this feature, so expect some splashing when accessing plumbing elements like the pump strainer lid, and unions.

Step 4

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

Check the rubber gasket for cracks pinching the gasket into a smaller loop. Cracks will look like striations across the length of the gasket.

Warped or stretched gaskets are evident when the o-ring sits in the groove o-ring, spilling over. The warping of an o-ring can lead to it being pinched creating a gap through which air can enter the plumbing.

If necessary, replace with new gasket, after cleaning the o-ring’s groove of gunk and leftover lube. Apply a new coat of lube, as well.

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Step 5

Your pump housing’s drain plugs are often overlooked when diagnosing an air leak, but these little gasket-sealed ports cause havoc if the seal is broken. Use any of the air leak techniques mentioned above or do an eye inspection for a pinched or defective gasket.

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Step 6

If your pump strainer gasket wasn’t the issue, move forward to the pump union. Most pumps have a union on their intake, this allows for easy maintenance and removal. These unions have a single gasket that seals the cuff and screw on adapter. Most commonly these o-rings become pinched. Go through the checks of the o-ring mentioned in the previous step

Step 7

PVC plumbing glued joints like tees, elbows, and valve ports are another common culprit. The epoxy sealing these joints can become brittle and washout overtime. This can create a progressively worse and worse air leak leading to complete pump priming failure.

The smoke, soapy water, or shaving cream method is the standard way of finding these leaks. Repair can be as simple as adding a caulk patch. Or if you want to ensure a permanent fix, re-piping and gluing will be necessary.

Step 8

If your air leak problem only occurs when you attach your vacuum hose, then the issue maybe pinhole-sized leaks in one or multiple hose sections. To find and replace these hose section:
  1. Disconnect all hose sections
  2. Use tape or plugs to seal the end of each section
  3. Submerge the hose section, while looking for any stray air bubbles coming from the body of the hose
  4. Complete this for each hose section, replace the sections with holes
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Step 9

If you still have a significant number of air bubbles coming out of your return lines into your swimming pool, you may have a bigger problem like leaks in your underground lines. Call a pool maintenance professional to help you isolate your problem.

Comments

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(361 to 400 of 604)

InyoPools Product Specialist  Posted: 2/22/2016 

Sid - You may have low water pressure in your whole system. See our guide on "How to Correct Low Water Pressure in Your Pool System". Check for a clogged impeller first. That is a common problem.
 Reply

 Posted: 2/22/2016 

I have low pressure in my automatic pool vac, it moves very slow. I recently got a variable speed pump to replace my old one. I have it set to 30 psi (filter reading), to at least get some water movement through the filter. The pump intake water pressure is very low and the water does not fill the basket area. It's less than half. Not sure if I have a leak in the system, don't see any visible leaks and pool water level is not dropping
 Reply

 Posted: 2/21/2016 

Thanks very much.!!!
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InyoPools Product Specialist  Posted: 2/9/2016 

Julie - Can you shut off the water to the filter then after the filter to see which way the water is draining when the pump is off. Then concentrate on finding problems in lines before or after the filter. Where is your current check valve before or after the filter. Most are after. If water is draining back into the pool through the pump, you might consider putting a check valve in the line before the pump.
 Reply

InyoPools Product Specialist  Posted: 2/9/2016 

Thomas - Bearings can be tricky to replace. If they are not lined up correctly, they can cause drag on the motor and end up overheating the motor and tripping the override protector. Does your motor feel extremely hot when it shuts off?
 Reply

 Posted: 2/8/2016 

HELP! When the pool turns off at night the filter "gurgles" all night. Sounds like water is leaving (or air is getting in?) We had someone come out and were told it was probably the check valve. We replaced it yesterday and last night it seemed worse!! No one seems to be able to help us. The filter is right outside our bedroom window so we ran the pool all night instead of listening to it gurgle. Any suggestions??
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 Posted: 2/6/2016 

I have a variable speed motor (A O Smith) It has a prime mode when the pump starts. Pumps fine no bubbles at outlets at the end of the prime mode it says prime fault. Worked fine till I replaced the bearings. Runs great just won't continue runing
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 Posted: 1/29/2016 

Simply the best on-line information site! Probably saved me hundreds possibly even $1000 in repair bills. Thank you
 Reply

InyoPools Product Specialist  Posted: 1/24/2016 

Airhead - Check around the discharge side of the pump for obvious water leaks, spraying, when the pump is on. I would think it would have to be a significant spray to allow the filter to drain. If this is a new system, water can drain out of the filter if it is installed somewhat higher than the pool water level.
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 Posted: 1/23/2016 

After the pump has been off for a bit (overnight), the filter has to refill with water. I've replaced spider gasket, filter gasket, pressure gauge. I noticed dampness around the bottom of the filter, no noticeable puddles though. Could a worn o-ring around on the drain plug allow enough water to leak/air to enter filter to cause this problem. Fix??
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InyoPools Product Specialist  Posted: 12/7/2015 

Louvis - If your sixth return port never worked since you purchased your pool/spa, I would guess that it was assembled incorrectly at the factory. Give us a call at 877-372-6038 and we can help you get this corrected. If it was working an recently stopped, you probably have a blockage in the system that would have to be blown out. The water lose may be due to evaporation or you have a slow leak somewhere in the system. Check to see if you can locate where water might be dripping out. Shut the pump off and drip some food coloring around possible areas like the skimmer base.
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 Posted: 12/5/2015 

I have a brand-new 8000 gallon pool /spa first problem one of the six returns is not working there is no circulation at the eyeball I even unscrewed the eyeball and stuck a Rod in there to see if it was clogged up but this did not correct the problem. Secondly my pool loses water volume when the pump is running basically it is 30 days old and everything is brand-new
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InyoPools Product Specialist  Posted: 11/16/2015 

Psykosoma - It sounds like water in the pipes (before the pump), is draining back in the pool after you shut off the pump. This can happen for a number of reasons not related to air leaks - like the pump being elevated above the pool surface. You may have to add water to the pump basket whenever you have to start the pump up or some people add a check valve between the pump and the suction inlets to keep the water from draining out when the pump is turned off.
 Reply

 Posted: 11/14/2015 

Hi. Hoping you can help. I have a Hayward Superpump that is having a problem self priming. It works fine once I fill the basket with water, but once the pump is shut off, I see a small amount of bubbles coming from the pool side inlet in the pump basket. After some time, if the pump is turned on again, it will not prime itself. I assume its an air leak on the suction side since that's where the air bubbles are coming from. I replaced the gaskets from the lid as well as the 2 gaskets between the motor and pump. Any ideas?
 Reply

InyoPools Product Specialist  Posted: 10/26/2015 

Joeyo - I'm not sure what you are asking. If you are trying to get water out of an above ground pool and you don't have a waste line, try this. Fill a garden hose full of water. Then, holding each end closed, place one end in the pool and trail the other end outside the pool down a slope. Gravity on the water in the hose will suck water out of your pool.
 Reply

 Posted: 10/25/2015 

Pool water level won't go down ,not evaporating..any ideas
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InyoPools Product Specialist  Posted: 10/5/2015 

Hey Mr. Wilson - Not sure what your pool issue is or where you have a leak. Air leaks occur in suction side of the pump as it is drawing in water from the pool. Pressure or water leaks occur on the discharge side of the pump returning to the pool. Both your heater and filter are on the discharge side of the pump so you would see them as squirts of water. Air leaks on the suction side are sucking in air so will not be as obvious. If your filter band is leaking (dripping, squirting), you should fix it as you indicated. When you replace the band, make sure to hit it lightly with a rubber mallet to make sure it seats evenly all around the band.
 Reply

 Posted: 10/4/2015 

thanks for the guidance on finding an air leak. I checked them all and the fittings to the heater were loose. I also cleaned the basket gasket and put more sealant and reapplied, thinking that would work. I noticed leaking from the filter band itself. So I guess I need to clean the filter, add DE and then re apply the large ring on the filter to be sure it's not leaking.

You didn't mention that in your helpful hints so I just thought I would say this OR if this can't cause the air leak, to maybe let me know.

Thank you!

 Reply

InyoPools Product Specialist  Posted: 9/10/2015 

bogie152 - Thank you for your suggestion to tighten the motor drain plugs. I will incorporate it in this guide.
 Reply

InyoPools Product Specialist  Posted: 9/10/2015 

m - Thank you very much for your comment. I will incorporate it into our guide.
 Reply

 Posted: 9/8/2015 

I too had major bubbles coming out of the return lines. I found that the drain plugs FOR (ON) THE PUMP were loose, probably from vibration over the years. I tightened the drain plugs and that took care of the problem
 Reply

 Posted: 9/4/2015 

also check noting is holding up the flap at the skimmer. this may not be obvious at first .
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InyoPools Product Specialist  Posted: 7/31/2015 

AHHHH! - Possible solutions depend on what filter you have. If it is a cartridge filter it may look clean but might be clogged with chemicals and oils that don't wash out. Try cleaning in a TSP solution or buy a new cartridge. If it is a sand filter, you may have a clogged breather tube or it may be time to change the sand (every 5-7 years).
 Reply

 Posted: 7/30/2015 

We spent an hour cleaning out our filter last night.. we have a 16x32 inground. and the filter and return started out really strong for like 2 hours, then it gets lower and lower and the pressure in the return is low and there is no suction. I checked the impeller and it seems there is no block.. the pressure gauge says 20 and its so not 20. there are some air bubbles in the return when we first put it on.
 Reply

InyoPools Product Specialist  Posted: 7/6/2015 

camp tagi - Thank you for your comment. This may also be a good way to find suction leaks. If you are filling the suction pipe at the skimmer under hose pressure and with the pump off, any leak on the suction side should squirt out instead of sucking in. You might be able to build up more pressure by placing the MPV in a "Closed" position to block off entry into the filter.
 Reply

InyoPools Product Specialist  Posted: 7/6/2015 

hatemypoolde - Sorry for the delay in response. We have had system problems too. Some of the common problems that might be affecting you: check to make sure that your impeller is not clogged; make sure you haven't put too much DE in your filter; try opening up your suction lines if you have diverter valves, then check your return lines. You might call Hayward at 866-722-2100 to see if they have any idea why you have to keep bumping your DE filter.
 Reply

 Posted: 7/2/2015 

get a "drain King" It screws on to the end of a garden hose .. put in it to the skimmer line and turn on the water. This will fill the line backwards with water and displace the air... if possible don't drain your system in winter unless there is a freezing potential. The drain king has a rubber bladder that seals off backflow thus making the line fill completely with water.
 Reply

Anonymous  Posted: 7/1/2015 

I HAVE REPLACED ALL THE SEALS IN MY PUMP BUT STILL HAVE AIR BUBBLES COMING OUT. i WAS THINKING i MIGHT HAVE A LEAK IN THE LINE GOING TO THE PUMP AND THE SKIMMER ANY IDEAS
 Reply

 Posted: 6/30/2015 

We're dying here. We had all kinds of suction problems last year with our above ground 5x24 round pool. We got so sick of it that we didn't even close it at the end of the year. It's July, we've been working on this since April and it's not even close to open. We have replaced everything except the motor which is only two years old. Our filter runs between 20 and 25 psi and the auction and return push does out a few minutes after the pump starts. We have to bump our Hayward EC-50 filter entry two to five minutes. At one point, we got the time up to 20 minutes but then we vacuumed the pool to waste, back washed the filter and the constant bumping started again. We spend ask day everyday working on this stupid pool and we don't seem to be getting any where. Help me understand what is wrong here. High pressure, low suction, low return, no leaks anywhere that we can find.
 Reply

InyoPools Product Specialist  Posted: 6/26/2015 

2yz4u - I would expect the pressure to drop at low speed. As long as your water remains clear, your system should be operating correctly.
 Reply

 Posted: 6/25/2015 

Hi...

I have a 12'x20' oval semi-inground. A Hayward Perflex DE filter (2013) & a new (2015) Blue Torrent 2-spd 1 1/2hp pump. The pressure on my filter has been 11 at hi-speed and barely registers a number at low speed. There are some bubbles coming out of the return, but the flow is sufficient (at low speed).

When the pressure is so low (3-5psi) is the filter still cleaning the water in the pool? The new pump was just installed (6/24/15) and the water clarity is crystal clear.

 Reply

InyoPools Product Specialist  Posted: 6/23/2015 

Poollady - First check of air leaks in the connections between the pool and the front end of the pump. Water may squirt out from backpressure when you turn the pump off. Then check your pump's impeller to see if it is clogged. See "How To Clean Out a Pool Pump Impeller". If that look good, pull the motor out of the pump housing and see if the impeller is loose or broken.
 Reply

 Posted: 6/23/2015 

I have 4 water inlets 3 have air bubbles and one does not, trying to track my problem. I think it could be within the pump impellar, what can I check?
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InyoPools Product Specialist  Posted: 6/22/2015 

Flyinghigh - Most filters have a breather tube going from the top of the tank to the bottom to release any air that is trapped in the top of the tank. Make sure that tube and the screen at the top are free of debris. Dumping a little extra Algaecide, would not cause this problem. Also check for small air leaks in the suction side of the pump by temporarily pasting the connections with plumber's putty.
 Reply

 Posted: 6/20/2015 

my pool opened up with no problems. Just a few days ago, I would shut down the pump and get that massive rush of backwash back into the skimmer basket followed by the skimmer lid popping off, etc. Turn it back on, and takes several seconds for the pump to re-prime itsel. After some troubleshooting, the severe bsckflush occurs with the Hayward XL Valve lever in filter ONLY. It does not do this backflush in recirculate or any other function. The pump even holds a prime with the lever in recirculate. I've checked the pump lid seal, with no difficiencies noted, followed by all pipe junctions screwed on tight, etc.

Any help would be appreciated! My initial guess would be the Hayward XL valve needs replacing. I also dumped a little extra Algaecide in the pool by accident. Could this be it?

 Reply

InyoPools Product Specialist  Posted: 6/18/2015 

Ranick - If you only see bubble when you first turn the pump on, that's normal. If you had a suction leak you would have air in your pump basket so that evidently isn't your problem. Try closing down the return jet diverter valve a little to balance the system. If your pressure is low, see our guide on "How To Correct Low Water Pressure in Your Pool System". Check your impeller to make sure it isn't partially clogged.
 Reply

InyoPools Product Specialist  Posted: 6/18/2015 

bmcg - Here's is a guide that shows you some of the common causes of low pressure: "How To Correct Low Water Pressure in Your Pool System". A clogged impeller [#6] is one of the most common.
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 Posted: 6/17/2015 

Pool is less then a year old. Had to fire the contractor so no warranty. Need help with this. The pump basket has no air in it but yet there are bubbles coming out of the return jets. Pool is a 18 x 36 with a 1.5 hp pump. Any ideas?
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 Posted: 6/17/2015 

I have a rod system using diatomite powder...im seeing constant low pressure out of my pool jet. pressure out of the filter into the heater seems fine, but then something is losing pressure between the heater and the jet.
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InyoPools Product Specialist  Posted: 6/17/2015 

needtoswim - If the bubbles only occur for a couple of minutes when you first turn the pump on, that's normal. Otherwise you may have a suction leak. Try putting plumber's putty temporarily around the outside of each of your suction connections. If the bubbles stop. look at the last connection puttied for your leak.
 Reply