You’ve just fired up your hot tub for a relaxing soak and noticed a problem… there’s no bubbles in the tub.
Bad news: This is likely the result of a hot tub air lock.
Let’s discuss what it is, why it happens, how you can fix it, and how to prevent it from happening again in future.
What Is “Air Lock” In A Hot Tub?
Air lock is essentially trapped air in the filtration system’s pipes.
It’s called “air lock” because the bubble(s) in the lines effectively locks the system, impeding water flow so that it can’t be returned to the tub via the return jets.
When you refill the hot tub with a hose, the water enters the filtration system through the jets, but it doesn’t always fill these lines evenly. When air in the pump and return lines mix they can create a block, preventing any more water from entering the return lines.
The biggest danger with air lock is that the lack of water can cause your pump’s motor to burn out if you run it for too long without feeding it any water.
Hot Tub Air Lock Symptoms
The most obvious sign you have an air lock problem is if you’ve turned on your hot tub jets and nothing comes out.
(If this happens, first double check your jets are actually open, as closed jets can mimic this issue.)
The other dead giveaway is when you hear a humming noise coming from either the jets or the pump.
This happens because the system, while technically operational, is jammed as it tries to move water but is blocked by the air bubble.
When you hear this noise you should turn the system off, as you can blow out the pump’s motor when water isn’t cycling through it.
How To Fix Air Lock (Troubleshooting)
An air lock can be fixed a few different ways, so we’ll go through each of the troubleshooting steps in more detail below.
Purge The Air In Your Jets
The first method works by slowly encouraging the air bubble(s) to move out of the pipes, effectively “burping” the hot tub.
Here’s how to do it:
- Start by putting the tub in priming mode using your spa’s control panel.
- Next, turn the jets on the “low” setting and let them run for 10 to 20 seconds.
- Finally, up the jets to the “high” setting, and run them for an additional 10 to 20 seconds.
Repeat this process 2 or 3 times. This should unclog the pipes and you’ll know once you see restored jet flow in the tub.
Bleed The Pump Valve (Of Air)
If the “burping” method doesn’t work, you can release the air in the lines by bleeding the pump’s air release valve.
This requires a bit more labor, but it’s an effective solution if the above steps didn’t work for you.
Here’s how to do it:
- Turn off the GFCI breaker to your hot tub so you don’t electrocute yourself.
- Remove your tub’s side panelling so you can gain access to the pump. This may require a screwdriver.
- Locate the bleeder valve on the pump (it’s usually on the face of the motor). Turn the valve’s nut to let air escape from the pump (you may need to use pliers for this part). You should hear a hissing sound which releases all the air, followed by a stream of water dribbling out.
- Tighten the bleeder valve.
- Turn the breaker back on and run the tub. The jets should be working again.
- If the jets are still locked with air, turn the breaker off again, and loosen the union fittings on the pump. Again, you may need a pair of pliers for this, and you should hear a hissing sound followed by a stream of water. Tighten the fittings, turn on the breaker and run the tub.
- Replace the side panelling and enjoy your jets.
Clean Your Hot Tub Filters
Your hot tub’s filter should be cleaned regularly so it doesn’t clog your system.
Regular filter maintenance should be performed every 2 to 3 weeks to clean out any debris that may be stuck in the tub’s skimmer, the cartridge filter itself, or at the entrance of the suction line.
Things like pebbles, dirt, twigs, and leaves can all compromise the filter.
You can simply hose off the cartridge to remove light debris on it, but you should deep soak the filter every 2 to 3 months. This will remove caked on residue and debris that requires a bit more strength to get rid of.
Check The Water Level
Hot tubs require a minimum water level in them at all times. Most spas will even come with a clearly marked waterline level.
The waterline is usually at the halfway point of the tub’s skimmer. If water drops below the skimmer, that means no water will enter the filtration system for cleaning and circulation.
Of course, no water in the system means no water coming back through the jets.
The pump will also continue to provide suction, but instead of taking in water, it will only take in air. As you might expect, this can cause serious damage to the pump and it may even need replacing.
Check For Leaks Or Damages
A tub with insufficient water flow coming from the jets could be dealing with a leak.
When water starts to drain out of the tub or filtration system, the water pressure drops, and there won’t be enough of it to send to the jets.
The spa can spring a leak virtually anywhere – the tub shell, valves, plumbing, lights, heater, and pump are all susceptible.
For more details on diagnosing and fixing a leak, check out our in-depth article on hot tub leaks.
How To Prevent Air Lock In Future
There’s no guaranteed way to prevent air lock from happening, but there’s one thing you can do to significantly decrease the chances when filling it up.
Air lock usually occurs when a hose is placed in the tub. As the water rises, it enters the jets’ lines, where air can be introduced.
To get around this, place the hose in the skimmer/filter well. The water will enter the system at this point and can flood the circulation system properly.
As the water makes its way out the jets and fills up the tub, it will push out any trapped air in the process.
Just Blow Off Some Steam
Broken jets should always be cause for concern, but hot tub air lock isn’t a major issue unless you run your system for too long.
Doing so can damage the pump, so you should be aware of the signs of air lock and how to fix it (which is easy to do) so you don’t gain an unexpected hot tub expense.