Pool Pump Series: Air Leaks & Loss of Prime – Why Your Pump Is Full of Bubbles
Noticing bubbles coming out of your pool jets or your pump struggling to stay full of water?
This is one of the most common pool issues and is usually a sign that your pump is pulling in air instead of water.
As part of our “Know Your Pool Pump” series, we’re breaking down air leaks and loss of prime, what causes them, and how to fix them.
What Does “Losing Prime” Mean?
Your pool pump needs to stay completely filled with water to work properly. This is called being “primed.”
When a pump loses prime, it means:
Air is entering the system
Water flow becomes inconsistent
Circulation drops significantly
Without proper prime, your pump can’t do its job effectively.
Why Air in Your Pump Is a Problem
Air in the system might seem minor, but it can lead to:
Poor water circulation
Reduced filtration
Increased wear on the pump
Overheating and potential damage
Left untreated, it can turn into a much bigger (and more expensive) issue.
Common Signs of Air Leaks
1. Bubbles Coming From Return Jets
This is the most obvious sign — air is being pushed back into the pool.
2. Pump Basket Not Completely Full
If you can see air gaps or swirling water inside the pump, it’s not fully primed.
3. Gurgling or Sucking Noises
Air entering the system often creates unusual sounds.
4. Pump Losing Prime After Turning Off
If the pump struggles to refill with water when restarted, there may be an air leak.
What Causes Air Leaks?
Most air leaks occur on the suction side of the pump (before the water reaches the pump).
Low Pool Water Level
If the water drops below the skimmer, the pump will start pulling in air.
Fix:
Keep water level halfway up the skimmer opening.
Worn or Dry Pump Lid O-Ring
The lid seal must be airtight. If it’s cracked or dry, air can enter.
Fix:
Clean and lubricate the o-ring
Replace if worn or damaged
Loose Pump Lid or Fittings
Even slightly loose connections can let air in.
Fix:
Tighten the pump lid and check all fittings.
Cracked Suction Lines
Underground or exposed pipes can develop small cracks.
Fix:
Professional inspection and repair may be required.
Blocked Skimmer or Suction Line
Restrictions in flow can cause the pump to draw in air.
Fix:
Clear baskets and check for blockages.
How to Fix Loss of Prime
Start with the simple checks:
Check pool water level
Clean skimmer and pump baskets
Inspect and lubricate the pump lid o-ring
Tighten all visible fittings
If the issue continues, it may require pressure testing or professional inspection to locate hidden air leaks.
How to Prevent Air Leaks
Maintain proper water levels
Regularly inspect and lubricate o-rings
Keep baskets clean
Ensure all fittings are secure
Schedule routine equipment checks
Prevention is the easiest way to avoid costly repairs.
When to Call a Professional
If you’ve checked the basics and your pump is still:
losing prime
full of air
or struggling to circulate
…it’s time to call in a technician.
Air leaks can sometimes be difficult to locate and may require specialised equipment.
Key Takeaway
Air bubbles and loss of prime are usually caused by small air leaks or simple maintenance issues. While they may seem minor, they can quickly affect your pool’s circulation and damage your equipment if left unresolved.