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What Is an Airlock in Your Bullfrog® Spa (and How to Fix It)

An airlock occurs when air becomes trapped in your spa’s plumbing, preventing proper water flow. This guide explains what an airlock is, how it happens, and how to safely remove it.

Overview

Your spa relies on continuous water flow through pumps and plumbing to power jets, filtration, and heating.

An airlock happens when:

  • Air gets trapped inside the plumbing or pump
  • Water cannot circulate properly
  • The pump cannot move water effectively

This most commonly occurs:

  • During initial startup
  • After draining and refilling your spa
Why Airlocks Matter

When an airlock is present, you may notice:

  • Jets not working or weak flow
  • Pump running but no water movement
  • Heating not working
  • Error messages related to flow

Because heating and filtration depend on water movement, an airlock can affect multiple systems at once.

How an Airlock Happens

The most common cause is improper filling.

When water is added:

  • Air pockets can remain trapped in plumbing lines
  • The pump fills with air instead of water

This prevents the pump from priming correctly.

How to Prevent an Airlock

The easiest way to prevent an airlock is during filling:

  • Remove the filter(s)
  • Place the garden hose directly into the filter compartment pipe
  • Fill the spa through the plumbing system—not the open shell

This allows water to push air out as the spa fills.

Quick Check

Before troubleshooting further:

  • Are pumps running but no water is moving?
  • Did this happen right after a refill?

If yes, an airlock is very likely.

Step-by-Step: How to Remove an Airlock

Step 1: Cycle the Pump

  • Press the Jets button on and off several times slowly
  • This can help push trapped air through the system

Step 2: Let the System Run

  • Allow the pump to run briefly
  • Sometimes air clears naturally after a few cycles

Step 3: Loosen a Union (Advanced Step)

If the airlock persists:

  • Turn off power at the breaker
  • Locate the pump union (connection fitting)
  • Slightly loosen it until you hear air release and water begins to seep out
  • Tighten it back securely

This allows trapped air to escape manually

Step 4: Use the Pump Bleed (If Equipped)

Some pumps have a bleed screw or nut:

  • Slightly loosen the bleed fitting
  • Wait until water flows steadily
  • Retighten once air is removed

Important:

  • Do not run Pump #2 during this step, as it may cause damage if air is present
Common Signs the Airlock Is Resolved

Once cleared, you should see:

  • Strong, steady jet flow
  • Normal pump sound (no cavitation or surging)
  • Heating resumes normally
Common Causes
  • Filling spa without using the filter compartment
  • Draining and refilling without proper priming
  • Air trapped in pump after maintenance
When to Contact a Dealer

Contact your authorized Bullfrog Spas dealer if:

  • Airlock persists after multiple attempts
  • Pumps are running but still no water flow
  • You are uncomfortable loosening plumbing connections
  • You hear unusual noises (grinding, loud humming)
What to Expect Going Forward

Airlocks are common and typically easy to fix.

With proper filling techniques and quick troubleshooting:

  • You can resolve most airlocks in minutes
  • Your spa should return to normal operation quickly
Confidence in Troubleshooting

Airlocks are one of the most common startup issues—but also one of the easiest to resolve. With a few simple steps, you can restore full water flow and get your spa back to normal operation.