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.

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.

Step 5

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

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

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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(1 to 40 of 532)

 Posted: 8/8/2019 

Hello, I recently installed an above ground pool 12x18 oval sand filter for my kiddies and not knowing anything about pools once the pool filled up I turned on the filter instead of backwashing it first causing the water to get cloudy...how can I get rid off this cloudiness in the water? First timer here and I have no idea what to do!
 Reply

InyoPools Product Specialist  Posted: 8/8/2019 

If the cloudiness is due to sand, you can wait for it to settle to the bottom of the pool then vacuum it up. If you think there is a chemical imbalance causing this issue, I would test the water to determine the steps needed to correct it. The fix could be as simple as adding some clarifier or adjusting your calcium hardness levels.
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 Posted: 8/7/2019 

What can be done if only one of the 4 return inlets have an air leak and poor flow?
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InyoPools Product Specialist  Posted: 8/7/2019 

have you checked any of the things mentioned in this guide? That would be a good place to start.
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 Posted: 7/8/2019 

Hi--how ofter do you need to replace an impeller? pump comes on but water wont circulate at all. no leaks I can determine.
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InyoPools Product Specialist  Posted: 7/9/2019 

Impellers only need to be replaced when they are broken. You may want to try reviewing this guide: How to Correct Low Water Pressure in Your Pool System
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 Posted: 7/3/2019 

Good morning. Water was exiting through my backwash hose during filtering and there was low pressure. I was told that it was most likely a faulty valve. The valve was roughly 7 years old. I replaced the valve (from INYOPools) and the same thing is happening. Water also runs out of the backwash hose when turning the handle to a different setting. On recirculate, the pressure is fine and no water exits through the backwash hose. I'm hoping you can tell me what the problem is here because I'm lost. Thank you!
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InyoPools Product Specialist  Posted: 7/3/2019 

A few things to check: Is the handle stiff or jiggly? A loose handle is the sign of a bad spring.If you open the valve, is the spider gasket still intact and secure in the groove? If not, then this may be the cause of the flow to the backwash.
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 Posted: 6/27/2019 

I seem to get air in lines but only when the skimmer inlet is used. The water level is perfect, psi with only bottom drain is 15, add in skimmer it jumps to 18. All normal, but air somehow gets in and psi starts dropping when skimmer is added.
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InyoPools Product Specialist  Posted: 7/3/2019 

The article mentions checking the pipe joints on the plumbing line. Since you have narrowed it down to the skimmer line, you can start there.
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 Posted: 5/11/2019 

Hello, my husband and I just bought a home with a pool. We have never had one before. We did everything as we should to open it except we forgot to take out the second plug in the jets. When we turned on the pump the pressure pushed out one of the plugs and a lot water was coming out of the one jet. We turned off the pumped and took out the rest of the plugs but we now have bubbles coming out of all the jets besides the one that pushed the plug out. The pump also has a lot of bubbles. Did we ruin the pipes or is it unrelated? Not sure if it was from that or if there is just an air leak somewhere. Hard to tell since we just bought the house.
 Reply

InyoPools Product Specialist  Posted: 5/14/2019 

Hello Courtney - A lot of air in the pump is a sign of an air leak. A common cause of air in the system, when opening the pool, is the absence of the drain plug(s) on the pump. They are removed during winterizing and sometimes placed in the pump basket. If that is not the issue, look for more common causes that are listed in the guide above.
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 Posted: 5/11/2019 

I recently had a new filter installed. The pump is new from the end of last summer. One of the exhaust lines in the pool was shooting out small bubbles. I added too much algaecide I believe, and now the filter PSI fluctuates and large bubbles come out of that exhaust line now and then. While raining now and there being less bubbles, no large bubbles from the line. Is it a algaecide issue do you think or possible piping issues to the exhaust?
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InyoPools Product Specialist  Posted: 5/14/2019 

Some algaecides do create foam and bubbles. If the problem persists, you may have a suction side air leak. The guide above explains where to check for the most common causes of an air leak. Issues on the return side do not cause air bubbles.
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 Posted: 5/2/2019 

Hi there. I recently replaced my filter grids with a complete grid/manifold kit. I did have to remove the whole filter unit so I could also replaced the filter units stripped drain plug. No leaks. Everything is working fine. Since doing that, I have what appears to be DE (cloudy water) in the filter basket at the pool pump. I can tell becuase the water in the pump filter basket gets all cloudy when I first turn on the pump. Also, I can see small traces of DE around my verticle bubblers at the steps too. I cannot see any DE actually blowing out the returns. Could this be a bad spider gasket or something else I could check first? Pentair Intelliflo and Pentrair FNS Plus 60.
 Reply

InyoPools Product Specialist  Posted: 5/2/2019 

Hello Houston - It could be a bad spider gasket. I'd also look at the o-ring on the standpipe. DE coming back into the pump could be an air leak or pressure side leak as well.
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Anonymous  Posted: 5/1/2019 

We had a replastering job done on our pool. When pool was refilled and started up, all was fine. I am now dealing with air bubbles coming from the farthest return. Can’t seem to find the problem. This was not an issue before the work was done. Any chance the replastering job damaged something?
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InyoPools Product Specialist  Posted: 5/2/2019 

The replastering and all the work it involves would take place in the pool basin. I'm not sure how that would create an air leak unless the workers fiddled with a valve or two.
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 Posted: 4/30/2019 

We recently replaced our pool pump and it primes right off the bat but then fills up with air slowly throughout the day while it's running. I've done the soapy water test and didn't see any obvious spots where it was being pulled in and checked the lid and seal there as well. We even had a professional come look at our equipment and he said it all seems to be running fine (he obviously saw it in the beginning of turning everything on while it was still primed) and that as long as water is always running through the system we are okay. He blew air through our lines and even took the pump apart to check for clogs at the impeller but found nothing. I know the pool is not pulling water in at all efficiently even if it is still pulling it in a little. The water was green (shock fixed that) but is still super cloudy and not filtering out all of the little particles. Am I missing some obvious fix here? I don't want to pay for another company to come look and tell me it's fine again when I know that it isn't actually working properly. Thanks for the help!
 Reply

InyoPools Product Specialist  Posted: 4/30/2019 

Hello Kelsey - What kind of pool pump did you install (single, dual, or variable)? Do you have the skimmer and main drain lines open? Is the water level halfway up the skimmer door opening?
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 Posted: 4/30/2019 

Hi Robert, we bought the pureline 1.5HP single speed pump to replace an old Hayward Super Pump 1HP. Our pool is super old (built in the 80's) so I've never found a valve that switches from the skimmer to the main drain so I'm not really sure on that one to be honest or if they are just both open all the time? And yes, the pool water is more than halfway up the skimmer so I don't think that is the problem.
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InyoPools Product Specialist  Posted: 4/30/2019 

Usually, the loss of prime is a suction side air leak. Assuming you don't have a suction side air leak, I'd take a look at the filter. A cloudy pool can bind up a filter rather quickly. Try cleaning that and see if your issue improves. 
 Reply

 Posted: 4/29/2019 

My psi seems to be fine when I first start my pump, but it goes up to 24 after a few hours. When I shut the pump off and release air through the valve on top of the filter, it seems to fix the problem when I turn it back on. I am going to try to go through the steps to find a problem, but do you have a good guess as to where to start?
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InyoPools Product Specialist  Posted: 4/30/2019 

Hello Skip - We'd be glad to assist you. Is the pool water clear or is it clear/green? What type of filter do you have?
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Anonymous  Posted: 5/1/2019 

It is clear. It is a hayward perflex extended cycle DE filter. I had a high level of phosphates, and that seems to have come down. The filter is running at around 12ish now.
 Reply

InyoPools Product Specialist  Posted: 5/1/2019 

A 12 PSI reading is good. If it continues to jump to 24 PSI quickly and the water is clear, you probably need to clean or replace the Perflex fingers. They can collect oils over time and a normal backwash won't work. They need to be soaked in a filter cleaner. If that doesn't work, they should be replaced.
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 Posted: 4/21/2019 

I have extremely low suction in my skimmer but really high psi. Normal for my oil is around 10 it’s currently at 25. I’ve cleaned the filter and backwashed and it will stay at 10 for about a half an hour and go right back up and hold at 25psi. Ive blown out the lines through the skimmer but I don’t know what else to do.
 Reply

InyoPools Product Specialist  Posted: 4/23/2019 

Hello Kimberly - We'd be glad to assist you. Is your pool water clear or is it cloudy/green?
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 Posted: 4/23/2019 

So I actually took my filter Completely out and cleaned it thoroughly as well as all the sludge at the bottom of the filter (so gross) I put it back in but I’m waiting to run it until my pool is clear of algae and debris. I’m circulating the water and using my Polaris and skimming the top but it is really cloudy still and I think that was making the filter clogged. Also I think the filter is pretty old (I just bought the house last August and the pool was already open then.) I bought a replacement grid and if the old one gets clogged again I’ll just replace it.
 Reply

InyoPools Product Specialist  Posted: 4/23/2019 

The filter is filling up quickly. That is why the PSI is rising and the suction from the skimmer is low. It will continue to do that until the pool is clear.
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Anonymous  Posted: 4/20/2019 

Air bubbles in skimmer return line. Checked for leaks and found nothing, water level ok. Today, we had a heavy rain and water level reached maximum level ( water above skimmer) ..... air bubbles disappeared? Any thoughts? Thanks much
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InyoPools Product Specialist  Posted: 4/24/2019 

Two things:1) Your water level was low, allowing your skimmer to gulp air. The heavy rain and raise in water level, fixed the issue.2) The heavy rain or a byproduct of it is now masking the effects of the leak but will eventually return.If you thoroughly checked all these steps mentioned in the guide before the rain, the issue should persist after it.
 Reply

 Posted: 4/12/2019 

I've been noticing the last couple of weeks that a gurgling sound would come from my pool every now and again. once I looked further into it. I noticed that it was releasing either air or water through one of the returns. this only happens after the pump is off, and it is through tout that whole down time.Any idea what could be causing it?
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InyoPools Product Specialist  Posted: 4/17/2019 

Hello Mario - Make sure your water level is halfway up the skimmer opening. Are you noticing air bubbles inside of the pump lid or bubbles coming out of the jets while the pump is running?
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 Posted: 4/4/2019 

I'm having an issue where my pool is only leaking when the pump is running. If I fill it up all the way and turn the pump on the water level stays the same but as soon as the pump is on it drops the water levels. Any suggestions to what is causing the leakage? I suspected the plumbing is bad but I don't really want to go digging if this is something much simpler.
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InyoPools Product Specialist  Posted: 4/9/2019 

If it only leaks when the pump is running, it must be something in the plumbing. We'd recommend trying a product called Fix-A-Leak.
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 Posted: 3/30/2019 

I've tried everything you suggested in all of these excellent troubleshooting steps, including the incense test. I have replaced the plumbing from the pump to the filter and installed a brand new Hayward Super Pump. Air bubbles are still being emitted from the jets.. I observed that there is a mixture of air and water rushing into the pump from the suction side if I only open the ball valve that controls the inflow from my vacuum system. More water flows in if I open the skimmer ball valve and/or the drain ball valve just a little bit Then the water flow seems normal. I pulled the ball valve out of the line that was letting air in I was able to get a snake to pass through from where the ball valve was installed into the pool but encountered no obstruction. There are air bubbles no matter which ball valve I open independently. I'm stumped.
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InyoPools Product Specialist  Posted: 4/9/2019 

Hello Stephen - It's possible that the pump is not able to pull enough water when you only open the vac line. Try opening the skimmer valve all the way. Does that eliminate the bubbles?
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 Posted: 4/9/2019 

I've tried each ball valve independently, but air bubbles never go away.
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InyoPools Product Specialist  Posted: 4/9/2019 

Have you tried completely opening all three? This way the pump can pull the water from the skimmer, vac, and drain at the same time.
 Reply