What Causes Air Bubbles in My Pool Return Jets?

Air bubbles are usually caused by air leaks in the pump system. Inspect the pump lid and plumbing connections for leaks.

Why Air Bubbles Are a Problem

A few bubbles here and there may seem harmless, but constant air bubbles in your pool return jets signal an issue in the circulation system. This means air is getting pulled into the suction side of your plumbing, interfering with proper water flow.

When too much air enters the system, it can reduce pump efficiency, damage the impeller, and allow debris to bypass the filter. Over time, this can lead to cloudy water, poor sanitation, increased energy usage, and even permanent equipment damage.

Air in the system also makes your pool noisier, with gurgling sounds at the pump and jets. It can create inconsistent chlorine levels due to poor circulation, causing algae or bacteria to flourish in dead spots.

Where the Air Is Coming From

The air in your return jets is almost always entering before the water reaches the pump. Common entry points include:

1. Low Water Level

• If your waterline drops below the skimmer opening, it can suck in air

• Creates turbulence and visible bubbles at the jets

Always keep the water level at least halfway up the skimmer for ideal operation.

2. Loose or Cracked Pump Lid

• A damaged or loosely sealed pump lid allows air to be drawn into the system

• Worn or dry O-rings on the lid can create invisible gaps

Check for signs of wear and lubricate the O-ring with silicone-based lube. Replace if cracked or flattened.

3. Faulty Unions or Fittings

• Unions and joints on the suction side may develop leaks over time

• PVC joints can shift or crack due to temperature changes or ground movement

Inspect these areas regularly and re-seal with Teflon tape or replace if visibly damaged.

4. Skimmer Weir Stuck or Missing

• The weir door helps regulate water flow into the skimmer

• A malfunctioning weir can create air vortexes that pull air into the suction line

Make sure it’s moving freely and not jammed with debris.

5. Cracked or Worn Plumbing

• Underground suction lines can develop cracks from age or shifting soil

• These are harder to spot without professional pressure testing

This is often the last thing to check after surface components have been ruled out.

Other Potential Causes to Consider

• Pump priming issues: If the pump struggles to prime, it’s likely drawing in air

• Valve leaks: Old or incorrectly set valves can allow air in

• Clogged skimmer baskets: Low flow can disrupt suction, introducing air

• Worn pump shaft seal: Allows air to enter from the motor side

A detailed visual and audio inspection while the pump is running can reveal subtle problems.

How to Troubleshoot Air Bubbles in Return Jets

Follow this process to systematically isolate and resolve the issue:

Step 1: Inspect Water Level

1. Check the skimmer box and ensure water covers at least half of the opening

2. Add water if needed using a hose

3. Reassess jet bubbles after topping off

Step 2: Examine the Pump Lid and O-Ring

1. Turn off the pump and open the lid

2. Inspect the O-ring for cracks or flat spots

3. Clean the sealing surface and apply lubricant

4. Replace if needed, then secure the lid tightly

Step 3: Check the Skimmer and Weir Door

1. Clear debris from the skimmer basket

2. Push the weir door gently to confirm it floats and moves

3. Replace if stuck or missing

Step 4: Inspect Unions and Fittings

1. Run the pump and listen near the suction line

2. Apply soapy water to fittings and watch for bubbles

3. Tighten loose parts or reseal threads

Step 5: Bleed the Filter

1. Locate the air relief valve at the top of the filter

2. Open slowly until water flows out steadily

3. Close the valve to restore pressure

Step 6: Look for Subsurface Leaks

If no surface issue is found:

• Monitor water loss over 24 to 48 hours

• Use the bucket test to rule out evaporation

• Contact a pool pro to pressure test suction lines

Tips to Prevent Air Bubbles Long Term

1. Keep the water level consistent

2. Inspect the pump lid and O-ring every time you clean the pump basket

3. Replace O-rings and gaskets at the start of every season

4. Maintain skimmer baskets and weir doors in good working order

5. Avoid running the pump dry during priming

6. Lubricate all gaskets and threads with pool-safe grease

Regular maintenance reduces the risk of suction leaks and helps your equipment last longer.

Tools That Help Detect and Manage Air Leaks

• Leak detection dye kits: Useful for above-ground leaks

• Digital pressure gauges: Help monitor pump and filter performance

• Flow meters: Identify reduced flow from air disruptions

• Stethoscope-style tools: Amplify suction-side leak sounds

• Visual inspection cameras: For checking underground lines

Using these tools early can save you from expensive damage down the road.

When to Call a Professional

Contact a pool technician if:

• You’ve checked all visible components and air is still entering

• The pump continually loses prime

• You suspect a break in underground plumbing

• Air bubbles worsen after cleaning or shock treatments

Professionals have specialized equipment to detect subsurface leaks, inspect valve seals, and conduct pressure tests that go beyond what’s possible with at-home troubleshooting.

A small air leak might seem like a minor nuisance, but it can be the beginning of major issues in your pool system. With regular checks, proper sealing, and timely repairs, you can keep your water clear, your jets smooth, and your equipment running trouble-free.