Ozone sanitation is a built-in hygiene feature on Ella jetted walk-in tubs, and the light humming noise it makes is completely normal. Whenever you run the hydro massage, an ozone generator releases natural ozone into the water system to eliminate mold and bacteria and to prevent mildew and odor from developing. It runs completely automatically, starts and stops with the hydro pump, and the only sign you may notice is a soft hum. It is eco friendly, uses very little power, and requires nothing from you.
Watch: Ozone Sterilization in Action

As the video says, ozone is a proven water disinfectant. It eliminates mold and bacteria from the water system and prevents mildew and odor from developing in your tub. Every time you turn your Ella walk-in tub's hydro massage on, rest assured it is being sanitized. Watch: Introducing Ozone Sterilization for Walk-In Tubs for Safe & Hygienic Bathing with a full transcript.
How It Works
- The ozone generator is wired to the hydro massage pump, so ozone sterilization activates automatically whenever the hydrotherapy jets run, and it runs for as long as the hydro jets are on.
- It draws only 0.04 amps, so it adds essentially nothing to your electric bill.
- Any Ella tub with hydro jets includes ozone sanitation, including the wheelchair transfer models. Air-only and soaking configurations do not have a hydro pump, so they do not carry an ozone generator.
Is the Humming Noise Normal?
Yes. When the ozone system is on by itself it makes a light humming noise. If you hear a soft hum when nothing else seems to be running, that is simply the ozone generator doing its job, and it is completely normal. It starts and stops automatically with the hydro pump, so there is nothing to switch off. A faint hiss from the small check valve on top of the unit is air being drawn through the generator, which is also normal, and a slight clean scent after the jets run clears quickly with the bathroom fan.
Does Ozone Replace Cleaning?
Ozone is a wonderful helper, but it is not a fully self-cleaning feature. It sanitizes the water lines during use, while your monthly routine keeps the whole tub fresh:
- Once a month, fill the tub to 1 inch above the highest jets, add 2 cups of white vinegar mixed with 2 cups of water, run the pumps for 10 minutes, then drain.
- Once a month, clean the pump inlet cover of hair and debris and wipe it with a non-abrasive towel.
- Wipe the surfaces regularly with a non-abrasive cleaner from the approved list.
Tubs with air massage have a second helper, the Auto-Purge cycle, which blows the air lines dry about 20 minutes after the air pump is switched off.

Can a Tub Be Ordered Without Ozone?
Our jetted walk-in tubs come equipped with ozone sterilization as a standard feature with the hydro package. Every Ella tub is made to order, so ozone can be excluded upon special request when you place your order through your Ella dealer or the team at (800) 480-6850. If you already own your tub and would prefer to run it without ozone, the disconnect guide shows the simple unplug procedure.
Ozone at a Glance
| Question | Answer |
|---|---|
| When does it run? | Automatically, whenever the hydro massage pump runs |
| Power draw | 0.04 amps |
| Sound | A light humming noise, completely normal |
| What it does | Eliminates mold and bacteria in the water system, prevents mildew and odor |
| What it does not do | It does not replace the monthly vinegar flush and surface cleaning |
| Which tubs have it? | Tubs with hydro massage jets; it can be excluded by special request on a new order |
Related Guides
- What Is Ozone Sterilization on a Walk-In Tub?
- Why Does My Walk-In Tub Ozone Generator Run All the Time, and Can I Turn It Off?
- How Does a Walk-In Tub Compare to a Hot Tub?
- What Is the Vinegar Flush on a Walk-In Tub?
- Ozone (O3) Button Does Nothing: Checking the Relay Click, the Air Tube, and Swapping Relays to Test
- Loud Noise From the Pump or Heater Area: What to Send Support and Why Ella Works Through Your Installer
Common Questions
Do I have to turn ozone on?
Does my tub have self-cleaning jets?
How long does the ozone cycle last?
The unit hisses or I smell something sharp. Is that normal?
Is ozone safe while I am in the tub?
Can I turn the ozone off but keep the hydro jets?
My older tub does not seem to have ozone. Can it be added?
There is a small black box with an air line under the tub. What is it?
Still need help? Open a support ticket at ellasbubbles.com/support or call (800) 480-6850 and the team will be happy to walk you through it.