Support Center / Maintenance & Cleaning / Why did my tub turn on by itself? Understanding the Auto-Purge air cleaning cycle
Back to Maintenance & Cleaning

Why did my tub turn on by itself? Understanding the Auto-Purge air cleaning cycle

Updated September 2026

▶Glossary7
  1. Watch: Auto-Purge Explained
  2. The Three Speed Air Massage and Auto-Purge Together
  3. Auto-Purge at a Glance
  4. Auto-Purge and Ozone: Two Different Helpers
  5. When to Reach Out to Us
  6. Related Guides
  7. Common Questions

If your walk-in tub turned on by itself a little while after your bath, or even while you are still relaxing in the water, that is the Auto-Purge feature, and it is completely normal. On tubs with the three speed air massage, about 20 minutes after you turn the air massage pump off the air system starts automatically and runs for 120 seconds (2 minutes), blowing air through its lines to clear out the water that naturally flows back into the piping so mold and mildew cannot form. It cannot be interrupted, it stops on its own, and there is no need to get out of the tub while it runs.

Watch: Auto-Purge Explained

Walk-In Tub With Air Massage and Auto-Purge Technology for Self-Cleaning
Chapters in this video
  1. 0:00 Activating Air Massage Speeds The video demonstrates how to gently push the button to cycle through high, medium, and low speeds for the air massage.
  2. 0:23 Understanding Auto-Purge Function The auto-purge function automatically activates 15 minutes after the air pumps are off and runs for 2 minutes to dry the lines.
  3. 0:50 Auto-Purge While Bathing The auto-purge may activate while a person is still bathing, which is normal and no cause for concern.
  4. 1:15 Gentle Button Operation It is important to push the buttons gently to avoid damaging the internal mechanism, and a palm push works for those with limited mobility.

Here is the guidance from the video, written out: Watch: Walk-In Tub With Air Massage & Auto-Purge Technology for Self-Cleaning with chapters and a full transcript.

  1. The air massage buttons work with gentle pushes: one push for high speed, a second push for medium, a third for low, and a fourth push shuts the system off. Do not press too hard or too deep, since pushing too hard may damage the internal mechanism. A gentle push with the palm of the hand works well for anyone with arthritis or limited mobility. Our hydro and air massage controls article covers every button.
  2. After the air pump is turned off, some water naturally flows back into the piping system. Left there, it would create mildew or bacteria.
  3. About 20 minutes after the pump shuts off, Auto-Purge turns on automatically and runs for 2 minutes, blowing air through the system and drying out the lines.
  4. This happens even if you are still bathing in the tub. There is no cause for concern. Just let Auto-Purge run its course and it will shut off after 2 minutes.
  5. You can exit the tub normally after draining, even while Auto-Purge is running. The tub will sound like it is still running, but it is only the Auto-Purge doing its job.
Close-up of an Ella walk-in tub interior showing the auto purge self-cleaning air jets running
Auto-Purge blows air through every air jet line for 120 seconds so no water is left standing in the piping.

The Three Speed Air Massage and Auto-Purge Together

Walk-In Tubs Featuring Three Speed Air Massage and Auto-Purge Technology
Chapters in this video
  1. 0:00 Innovative Jetting Design Ella's Bubbles walk-in tubs feature unique jet placement for a comprehensive hydro massage experience.
  2. 0:15 Three Speed Air Massage Our tubs offer a three-speed air massage system, activated by digital or Easy Touch push buttons.
  3. 0:27 Auto Purge Technology The Auto Purge system activates 20 minutes after use, clearing moisture to prevent mold and mildew.

This second video shows the air massage jets in the hip, foot, and bidet positions, activated by push buttons or the digital controller, and explains that the purge activates about 20 minutes after the tub is turned off to clear leftover moisture and prevent mold and mildew. If you have a printed manual that words the trigger differently, the operative facts are the same: automatic, about 20 minutes after shutoff, 120 seconds, self-stopping, and normal. Watch: Walk-In Tubs Featuring Three Speed Air Massage & Auto-Purge Technology with chapters and a full transcript.

Auto-Purge at a Glance

QuestionAnswer
Which tubs have it?Tubs equipped with the three speed air massage system
When does it start?Automatically, about 20 minutes after you turn the air massage pump off
How long does it run?2 minutes (120 seconds), then it stops on its own
Can it be stopped or adjusted?No, the timing is pre set and the cycle cannot be interrupted, and that is by design
Is it safe while I am in the tub?Yes, simply let it finish. You may feel a burst of air from the jets
What does it accomplish?It clears leftover water and moisture from the air lines, preventing mold and mildew

Auto-Purge and Ozone: Two Different Helpers

Auto-Purge belongs to the air system. Tubs with hydro massage also have an ozone generator that switches on with the hydro pump to sanitize the water and lines, and when it runs it makes a light humming noise, which is also normal. Our ozone sanitation article explains that side. Neither system replaces the monthly vinegar flush described in cleaning and monthly maintenance.

When to Reach Out to Us

A 2 minute purge cycle after each use of the air massage is healthy, normal behavior. If your purge cycle keeps running continuously and will not shut off after 2 minutes, turn the tub off at the breaker and contact technical support so we can check the control system with you; a stuck relay or control box is the usual cause, and our control box reset guide is a good first step. And if you ever see mold appear despite Auto-Purge, run the standard flush, 2 cups of white vinegar with 2 cups of water, filled 1 inch above the highest jets, pumps on for 10 minutes, then drain, and see black flakes or slime from the jets if it keeps returning.

Common Questions

Why did my tub turn on by itself after my bath?
If your walk-in tub turned on by itself a little while after your bath, or even while you are still relaxing in the water, that is the Auto-Purge feature, and it is completely normal. On tubs with the three speed air massage, about 20 minutes after you turn the air massage pump off, the air system starts automatically and runs for 120 seconds (2 minutes). This process blows air through its lines to clear out the water that naturally flows back into the piping, preventing mold and mildew from forming.
Is it safe to stay in the tub while it runs?
Yes, it is safe to stay in the tub while the Auto-Purge runs. You may feel a burst of air from the jets for about two minutes, and then the cycle stops on its own. There is no need to get out of the tub while it runs, but if you prefer to exit, you can drain and leave the tub normally, even while Auto-Purge is active.
Can I change the timing or turn Auto-Purge off?
No, you cannot change the timing or turn the Auto-Purge off. The timing is preset, and the 120-second cycle cannot be interrupted or adjusted. This design ensures that the air lines are always dried after use, preventing the formation of mold and mildew.
The purge will not shut off. What do I do?
If your Auto-Purge cycle keeps running continuously and will not shut off after 2 minutes, you should turn the tub off at the breaker. Then, contact technical support so our team can check the control system with you. A stuck relay or control box is the usual cause for a continuous purge cycle.
Auto-Purge only seems to blow through the small jets, and I see mold. Is something wrong?
Run the vinegar flush with every system on and repeat it if needed, and make sure the tub drains fully after each bath. If mold keeps appearing after two or three correct flushes, send photos through a ticket so the team can check the air lines.
My tub is hydro only. Does it have Auto-Purge?
No, a hydro-only tub does not have Auto-Purge. The Auto-Purge feature is part of the air massage system, which is not present in hydro-only tubs. Hydro-only tubs rely on the ozone generator, which runs with the hydro pump to sanitize the water and lines, in addition to the recommended monthly vinegar flush for maintenance.
What is the light humming noise when nothing is running?
The light humming noise when nothing else is running is the ozone generator, which is normal. The ozone generator switches on with the hydro pump to sanitize the water and lines. Auto-Purge, on the other hand, sounds like the air jets running for two minutes as it blows air through the system.
Which push order controls the air speeds?
To control the three-speed air massage, press the Air button gently. One push activates high speed, a second push sets it to medium, a third push selects low speed, and a fourth push shuts the air massage system off. Pushing too hard or too deep may damage the internal mechanism, so a gentle push with the palm of the hand works well, especially for those with arthritis or limited mobility.
I killed the power before the purge ran. Is there a way to purge the air lines manually?
Cutting the power cancels a pending purge. To purge manually, restore power, run the air massage on high for a moment, then turn it off so the timer restarts; the purge follows about 20 minutes later and runs for 120 seconds. It blows at slightly higher pressure than the high air setting, and skipping it leaves stagnant water in the air lines.
Can the purge be left off my order?
No. The auto purge is part of every air massage package, not an accessory, and it cannot be disabled. Together with the ozone that runs with the hydro pump, it is the reason the air and hydro lines stay clean between baths.
The air came on after a bath where I never used the air massage. Why?
On some control boxes, turning another component off, such as the chromatherapy light, can also start the Auto-Purge timer. This means a purge cycle can follow a bath even if the air pump was never used. This behavior is harmless and completely normal for your walk-in tub.

Still need help? Open a ticket at ellasbubbles.com/support or call (800) 480-6850 and our team will be happy to walk you through it.

About this guide. Answers in the Ella’s Bubbles Support Center are compiled from real conversations with tub owners, our technicians’ notes and the product documentation, then reviewed by our team. Tub models and options have evolved over the years, so a detail here may differ slightly from your exact tub. If something looks different on yours, send us your serial number and a specialist will confirm it for your model.

Related guides

Did this solve your question?

If not, open a ticket and our team will pick it up from here.

Open a Support Ticket