Last Updated: March 1, 2021

How to Find and Fix Pool Pump Air Leaks

Written By: Pool Care Guide

Have you noticed air bubbles in your return line or a lack of air pressure in your pool pump? There are a small handful of locations where air leaks tend to happen. In this article, we will show you where to check for those leaks and what to do about them as you find them. Before we get deep into it, here’s a quick reference list of the areas and causes we are about to investigate:

  • Common Areas
    • Low Water Levels
    • Strainer Lid and Its Gasket
    • Pool Pipe Unions
    • Skimmer Weir (Not leak, but causes low pressure)
    • Pump Housing Drain Plug
    • PVC Pipe Joints

Air Leaks on the Suction Side
Water Leaks on the Discharge Side

Pool pumps have two sides to them. There is one side that pulls the water into the filtration system, and the other side discharges it. Because Knowing this gives you a narrow list of places to check for air leaks.

We want to say that air leaks are always on the suction side, and water leaks are always on the discharge side. However, there are oddball scenarios that can contradict that. Instead, we will say that this is the case over 99% of the time. It’s safe enough to assume.

Common Areas and Causes of Air Leaks

Low Water Levels

Let’s start off with your pool’s water level. Some may not know this, but the common recommendation is to fill your pool to the point of meeting the midpoint of the skimmer. This is the recommendation for two reasons.

First, the pool’s filtration system needs a constant source of water. That water is pulled from two sources. The first is a drain at the bottom of the pool. Second, is the skimmer or skimmers if the pool is large. When the water doesn’t quite reach the skimmer, that skimmer can’t let air into the pool pump.

Second, water needs to reach the skimmer midpoint to collect debris. A lot of debris floats on top of the water. If the water level is at the midpoint of the skimmer, the water pouring into the skimmer will create a current that pulls debris into the skimmer basket.

Solution

The obvious solution to a low water level is to add more water. Toss a hose into the pool and let it fill.

If this is a common occurrence and even if it’s not, we recommend investing in a water leveler. You can get some cheap water levelers for under $50, and they will ensure that your water always stays at the ideal level. 

Strainer Lid + Gasket

While we are looking at the strainer lid, we should examine it for any cracks or defects. If there is a problem, it likely won’t be on the lid. It will probably be found in the gasket/o-ring. Gaskets work as a seal between two hard surfaces so that air or liquid cannot pass through the two surfaces.

In order to be useful, the gasket must be whole and maintain its rubbery, soft, and pliable properties. The pliability allows the gasket to conform to any uneven surfaces

Unfortunately, over time, gaskets fray, crack, and contort, and ultimately become useless.

Solution

If the gasket on your strainer lid has degraded, it will need to be replaced. Eventually, all gaskets need to be replaced, but their life spans can vary greatly. One gasket will last a year and another will last a decade. You can extend the lifespan by occasionally wiping it clean of dirt and applying grease as needed.

Pool Pipe Unions

Sometimes, the pool pump pipes develop leaks at the union fittings. These Union fittings will look something like this picture.

As far as air leaks go, we are primarily going to suspect the pipe union on the suction side of the pool pump. If you open yours up, you should find another gasket / o-ring. 

Solution

Before you do anything, turn off the power to the pool pump. When the power is off, check to make sure that the gasket is in good condition and doesn’t need to be replaced. Use the same criteria as the strainer lid gasket. If worn, cracked, or bulging, replace it with a new gasket and lube that gasket. Use silicone lube or some other lube formulated for pool applications.

When you reattach the union, tighten it with your hands and not with tools. The unions are easy enough to tighten by hand, and using tools risks the potential for breaking the union.

Skimmer Weir 

This isn’t technically a leak. However, it can easily trick a pool owner into thinking that there is an air leak, so we are going to include it. The skimmer is where the pool water is pulled into the pool filtration system. As the water pours into the skimmer, it generates a current that pulls debris into the basket that sits in that skimmer. The skimmer weir is a vertical revolving door that keeps the debris trapped inside of the skimmer basket. 

When the skimmer weir is functioning correctly, the pool pump’s current is what opens the skimmer weir door to let debris and water inside it. Sometimes, this skimmer weir door breaks or gets stuck. When the skimmer weir can’t open and the pool pump is running, the water cannot enter into the skimmer fast enough to keep up with the pool pump’s demand. This causes the pool pump pressure to drop which makes it look like there is a leak.

Solution

If the skimmer weir is broken, then you will need to replace it. If you need help with that, we did write up a short guide on How to Replace a Skimmer Weir. Replacing a skimmer weir is a simple process, so the guide probably isn’t necessary. Still, it’s there if you would like some step-by-step help.

Pump Housing Drain Plug

Underneath the pump housing, there should be a drain plug. As with most of the potential air leak sources, the drain plug is reliant upon an o-ring/gasket to make a secure connection. Frayed, cracked, contorted, or hardened gaskets are mostly useless.

Solution

We are sure that it is obvious at this point. Clean out the groove where the o-ring / gasket sits. After that, replace any old and busted gaskets with new and silicone-lubed gaskets.

PVC Pipe Joints

Check the PVC pipes. Were they put together with care or haphazardly shoved into place? The joints should be your main area of focus. Were the joints fully coupled and cemented together?

Solution

If they are not cemented or the connections are insecure, you should remake those connections. If there is cement but a joint’s connection is bad, you will need to cut out and throw away any of the affected pipelines and joints and then replace them. We can give you a brief rundown of what you’ll need and what to do. However, we recommend finding one of the many YouTube videos if you need 

A quick word of warning - When we say to cement the joints, we are not talking about gluing the unions closed. Those need to be able to twist off and back on again.

Here’s a quick shopping list that you’ll need if you are going to replace the pipe:

  • Hack Saw
  • PVC Primer
  • PVC Cement
  • Replacement Pipe
  • Replacement Joints
  • Coupling(s) - This is situationally dependent, and it is explained in the first step.
  • PVC Cleaner (Optional)
Step 1: Prepare Your Shopping List

You’ll need pretty much everything on the list above. The cleaner is optional. Some like to use it, but you will be fine without it. You really only need a clean rag and some water.

As far as the couplings go, the amount that you need will be dependent upon the size of the damaged leaky section and if there is more than one. If the section that you need to remove from the pool pump’s PVC pipe is small. You might only need one coupling. In order for this to be true, the removed section will need to be smaller than the length of the coupling. This is because the coupling must be able to breach the newly created gap. 

Also, the two still connected pieces of PVC will also need to be close enough to be pushed completely into the coupling that you are adding. . It will need to be small enough of a removed section that it leaves enough remaining 

Step 2: Cut out the Bad Section

Self-explanatory. We will only make one note. Try to make the cuts as straight as possible. If the cut is made at an angle, it affects how fully and securely the new connection will be. It would be a shame to do all the work and end up with another air leak in the pipe.

Step 3: Clean

Wipe down the exterior of the pipe and the interior of the connections. It doesn’t need to look perfect, but it should feel smooth to the touch. 

Step 4: Add PVC Primer

It might not be noticeable, but the PVC primer makes the pipe soft and pliable and it evens out the surface for a better connection between the pipe and the connecting piece (joint or coupling).

Add the primer to the exterior of the pipe and the interior of the connecting piece. Do not wait for the primer to dry. For the best connection, the primer should still be damp.

Step 5: Add the PVC Cement

Ideally, you’ll have the cement applied within 10 seconds of applying the primer. However, it will be fine if it takes you a little bit longer than 10 seconds.

PVC cement dries within a couple of minutes, so connect everything together as quickly as possible. As you are putting the pipe into the connector, give it a quarter twist. This twist will spread the cement and increase the success of the bond.

The cement will need to dry, so hold the pipes and connector together for at least 30 seconds. At this point, some people wait for roughly 20 minutes, but it isn’t entirely necessary. The cement’s grip solidifies quickly, so it shouldn’t fall apart.

Step 6: Wait before Turning on the Water

You should refer to the instructions on the PVC Cement label, but it will probably tell you to let the cement cure for about a day. We don’t usually wait that long before turning on the water, but we don’t feel comfortable recommending it just in case it causes problems.

In Conclusion

There are 10,000 ways that machines can break, so do not consider this to be an exhaustive list. We’ve listed the more common issues, but there are others out there. Use your eyes and ears. Look at connections, corners, tubes, and parts worn down by time and weather.

If you think there are other types of air leaks that should be included, let us know. We are happy to do more research and write more articles if it helps our readers.

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