Why Does My Walk-In Tub Smell Like Ozone or Chlorine During Hydro Massage?

The smell is ozone, not chlorine. Every Ella tub with hydro jets has a small ozone generator that releases natural ozone into the water system whenever the hydro pump runs, and ozone has a clean, slightly metallic scent that is easy to mistake for chlorine. It is normal, it means the sanitation system is doing its job, and it clears quickly with the bathroom fan. The same odor is covered from the metallic angle in Why Is There a Metallic Smell When the Jets Run?.

Why It Cannot Be Chlorine

A hot tub holds the same water for an extended period and relies on chlorine, bromine, shock and pH balancers, plus filtration and a pump that cycles around the clock, to keep that water safe. An Ella walk-in tub works the other way around. It fills with fresh water for every bath and drains completely afterward, so there is nothing to sanitize, balance or test, no filter cartridge to rinse or replace, and no chemical to add. Because you never put chlorine into the tub, the pool-like note you notice during hydro massage is ozone produced by the generator and carried into the circulating water. The full comparison, including why the pumps run only while you bathe, is in How Does a Walk-In Tub Compare to a Hot Tub?.

Where the Ozone Comes from

The ozone generator lives under the deck and is wired in line with the hydro massage pump. When the hydro jets start, a small check valve on top of the unit draws air through it, ozone is produced, and the ozone is carried into the water moving through the jet lines. Ozone is a proven water disinfectant: it eliminates mold and bacteria from the water system and prevents mildew and odor from developing in the lines. The video on this page introduces the system and makes the same point, that every time you turn the hydro massage on the tub is being sanitized. The generator draws only 0.04 amps, so it adds essentially nothing to your electric bill, and it needs nothing from you. It is a hygiene feature rather than a therapy, and it exists only on tubs with hydro jets. Air-only and soaking configurations have no hydro pump and no ozone generator, so an air-only tub does not produce this smell. The background, including why the unit hums softly on its own, is in What is ozone sanitation, and is the light humming noise from my tub normal?.

How to Confirm the Smell Is the Ozone

1. Fill the tub to at least 1 inch above the highest jets and start the hydro pump.
2. Notice whether the smell arrives with the jets, and whether you can also hear the light hum of the generator and the faint hiss of air at the check valve alongside the moderate hum of the water pump.
3. Turn the hydro pump off. If the smell and the hiss stop with the pump, the ozone generator is the source and nothing is wrong.
4. Run the bathroom fan. The slight clean scent left after the jets run clears quickly with ventilation.

On a new or recently serviced tub the smell is usually more noticeable than it will be once you are used to it. It does not build up from bath to bath, because the water that carried the ozone goes down the drain when the tub empties and the next bath starts with fresh water. The smell is tied to the hydro pump, so a soak with the jets off produces none of it, and an air massage session on a dual massage tub does not produce it either unless the hydro jets are running at the same time.

When the Smell Is Not Normal

The normal ozone scent is faint. A smell that is strong enough to be unpleasant, that continues after the hydro pump stops, or that comes with a loud rattle rather than a light hum is a reason to unplug that component and open a ticket. A burning smell is different again: switch the tub off at the breaker and leave it off until it has been checked. The distinction between a faint clean scent and a smell that needs attention, along with the other sounds a tub makes, is in Why Does My Walk-In Tub Make a Buzzing or Hissing Noise?. For the ticket, send a short video with sound, a photo of the generator and its T connection under the tub, and your model and serial number to ellasbubbles.com/support, or call (800) 480-6850.

If You Would Rather Not Have the Smell at All

The generator can be disconnected without affecting the hydro massage. Turn off power at the GFCI breaker, remove the access panel, locate the power cord from the ozone generator and the T connection that joins it to the hydro pump, disconnect both ends of the T, cable-tie the ozone cord to the tub frame so it stays clear of moving water and equipment, and plug the hydro pump directly into the plug from the central control box. Test the hydro pump afterward to confirm it starts and stops normally, and reverse the steps to reconnect. The steps and the video are in Disconnecting or Servicing the Ozone Generator on Your Walk-in Tub. Disconnecting is appropriate as a personal preference, but the system is a chemical-free helper and most tubs are best left connected. Either way, ozone only sanitizes the hydro lines during use and does not replace the monthly flush: 2 cups of white vinegar with 2 cups of water, added to a tub filled 1 inch above the highest jets and run for 10 minutes, then drained.

Watch: Introducing Ozone Sterilization for Walk-In Tubs for Safe & Hygienic Bathing | Ella's Bubbles with chapters and a full transcript.

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