How to Fix a Hot Tub Air Lock (and Prevent It)

We've been there ourselves, lining up everything just right for a nice soak, only for the jets to sputter and then stop entirely, leaving us frustrated. A hot tub air lock is a common problem that happens when air becomes trapped in the plumbing lines after a refill. This airlock blocks water flow, making it difficult or even impossible for the hot tub pump to circulate properly.

It can happen right after you drain and fill your spa, especially if the water isn’t added correctly. Signs of an airlocked pump include weak or inactive jets, a pump that hums without pushing water, or a system that’s running but only produces air bubbles, not water.

In this guide, we’ll walk you through how to spot an air lock, what causes it, and how to fix it using proven methods, so your tub returns to normal operation quickly, safely, and without damage to your system.

What Is a Hot Tub Airlock?

A hot tub airlock occurs when air becomes trapped in the plumbing lines during or after a refill. When this happens, the air disrupts water flow and prevents the hot tub pump from operating as it should. It’s a frequent issue for hot tub owners, especially after draining and refilling the tub without taking precautions.

In many cases, the pump still runs, but it struggles to push water through the system. As a result, the jets may weaken or stop altogether. This happens because air, unlike water, doesn’t allow pressure to build properly inside the plumbing. That trapped air must be released for the system to return to normal flow.

Since hot tubs are designed with closed plumbing lines that keep water circulating, even a small amount of air can act like a plug. Until the airlock is cleared, your spa’s water circulation and overall performance will remain compromised.

Symptoms: How to Tell If You Have an Air Lock

After refilling your spa, you might notice the system powering on, but with little to no movement through the jets. This is a clear sign of a hot tub airlock. In this situation, the pump is active, yet water flow is blocked by air trapped inside the plumbing lines.

An airlocked pump will hum or run without circulating water. It’s a common problem that can occur even when the water level appears normal. Instead of steady water flow, you may see air bubbles or feel jets blowing air, not water. These are all signs that air has entered the system and is preventing normal function.

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If left unresolved, the pump may overheat or shut off for safety.

Step-by-Step: How to Fix a Spa Air Lock

Fixing a hot tub air lock starts with releasing the air trapped inside the plumbing lines. These straightforward methods can help restore normal water flow and prevent long-term damage to your hot tub pump, heater, and system.

Method 1: Open the Bleed Valve

• Locate the bleed valve near the pump and carefully open it.
• You’ll likely hear air escaping. Wait until a steady stream of water begins to flow.
• Once water runs smoothly, tighten the valve to seal the system.

Method 2: Loosen the Pump Union

• Turn off power to the tub.
• Find the union fitting near the pump and gently loosen it.
• This will allow air trapped in the plumbing to escape.
• After a short release, tighten the union back into place.

Method 3: Use a Garden Hose

• Insert a garden hose into the filter canister or directly into one of the jet lines.
• Push water through the system to displace any remaining air pockets.

Method 4: Switch Jets On and Off

• Use your control panel to cycle the jets on and off several times.
• This method changes pressure in the plumbing lines and can help move trapped air out of the system.

Method 5: Check for Debris

• Remove the filter and inspect the area for debris.
• Sometimes blockages prevent water, not air, from circulating properly, mimicking the symptoms of an airlocked pump.

For more details, read: Expert Hot Tub Filters Guide – Everything You Need To Know

What If These Methods Don’t Work?

If the airlock remains after trying the steps above, there could be a deeper issue with your spa system. Watch for other signs:

• A clogged filter blocking water flow
• Debris lodged in the plumbing lines
• A damaged or overheated pump that hums but doesn’t move water
• Cracks, leaks, or faulty connections allowing air to enter
• Constant air bubbles, even after bleeding the lines

In some cases, a broken valve or malfunctioning heater may be drawing air into the system. If your hot tub still won’t circulate water, it’s best to call a qualified technician.

Ignoring the issue could lead to permanent damage to your pump or other components.

Prevention Tips: Avoiding Future Air Locks

Hot tub airlocks are easiest to prevent during the refill process. A small oversight, like letting air enter the plumbing lines, can lead to weak jets, air bubbles, or even an airlocked pump. But with a few simple steps, you can avoid this common problem altogether.

Here’s how to refill your tub properly and keep the system air-free:

• After draining the spa, insert a garden hose directly into the filter canister or plumbing line
• Fill the tub slowly to avoid trapping air
• Watch the water level as it rises, ensuring it fills evenly
• Once filled, simply turn on the pump and check for water flow
• Open the bleed valve to let out any remaining air

Avoid turning on the pump while air is still trapped in the system. Doing so can damage your hot tub's internal parts like the heater, jets, or plumbing unions.

A careful refill takes only a few extra minutes and can save you hours of troubleshooting and potential repairs later on.

How O-Care Helps Maintain a Healthy Spa System

A well-maintained hot tub system is far less likely to develop an air lock, and that’s where O-Care makes a real difference. By using O-Care weekly, you help keep your spa’s plumbing lines, filter canister, and pump clean, balanced, and free from buildup.

O-Care minimizes the risk of debris and biofilm clogging the filter or restricting water flow. This protects against issues like air bubbles in the jets, air trapped in the plumbing, or an airlocked pump after a refill. When the system stays clean, it becomes much harder for air to enter and block circulation.

Because it’s made from high-quality mineral salts, O-Care is gentle on your tub’s components. It helps extend the life of the hot tub pump, heater, and valves, reducing the chance of leaks or damage over time.

With consistent use, your water stays balanced, your system performs as it should, and common problems like trapped air or reduced water flow are less likely to occur. O-Care helps keep everything running smoothly, so your spa remains a space for pure relaxation.

Ready to protect your hot tub? Access our store locator to find O-Care near you!

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Conclusion: Fixing Air Locks Is Simple with the Right Steps

A hot tub air lock is a common problem that often occurs after draining and refilling the spa, but it doesn’t have to be a major setback. In most cases, releasing the trapped air is straightforward and can be done safely at home.

Whether you open the bleed valve, loosen the pump union, or use a garden hose to push air from the plumbing lines, each method helps restore normal water flow. If your filter is clean and your system is in good shape, the pump should return to normal operation without further issues.

No specialized tools are needed, just a little attention to detail during your refill. With routine care and proper maintenance, you can prevent air from getting trapped in the plumbing and keep your hot tub running smoothly for the long haul.

Find your nearest O-Care retailer – Store Locator.

FAQ: Answers to Common Air Lock Questions

Can an airlock damage my hot tub pump?

Yes. When air becomes trapped in the plumbing lines, the hot tub pump may run dry without circulating water. This lack of water flow can cause the pump to overheat, trigger an automatic shutdown, or in more serious cases, result in permanent damage to internal parts. Left unresolved, an airlock can lead to costly repairs.

How long does it take to bleed a spa air lock?

Bleeding an airlocked pump typically takes just a few minutes. You can open the bleed valve or carefully loosen the pump union to release the trapped air. Once water starts flowing consistently through the plumbing, tighten the valve and check for full circulation throughout the system.

Is it safe to use the spa if I suspect an air lock?

No. Running the spa while air is trapped in the system can cause serious harm to components like the heater, pump, or internal seals. Always clear the air lock first to avoid mechanical failure, leaks, or overheating.

Will turning the jets on and off help clear it?

Yes. Rapidly cycling the jets on and off can help shift pressure in the plumbing lines and dislodge air trapped in the system. This method works best when paired with others, like opening the bleed valve, using a garden hose, or refilling the tub slowly and properly.

Should I call a technician or try to fix it myself?

If your pump still won’t circulate water after trying basic methods like bleeding the system or checking for debris, it’s time to call a qualified technician. Continuing to run an airlocked system may worsen the issue and damage vital parts such as the pump, filter, or pipes.

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