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Why Is There a Metallic Smell When the Jets Run?

Updated September 2026

A faint metallic smell when the jets run on a hydro tub is almost always the ozone sanitation system doing its job, and it is normal. Ozone is not a therapy; it sanitizes the hydro jet lines against mold and scum, it runs automatically whenever the hydro pump runs, and it exists only on tubs with hydro jets. The small generator also makes a light hum or hiss on its own, which is expected. The first thing to check is simply whether the smell and sound stop when the hydro pump stops, because that confirms the source. If you would rather not have it, the generator can be disconnected. The background is in ozone sanitation explained.

Likely Causes

  • The ozone generator is running with the hydro pump, producing its characteristic clean, slightly metallic smell.
  • The light hum or hiss you hear is the generator itself, a small unit rated 0.04A, which is normal.
  • The tub is new or recently serviced, so the smell is more noticeable than it will be once you are used to it.
  • You would prefer the system off, which is possible by disconnecting the generator.

What to Check, in Order

  1. Run the hydro pump with the tub filled at least 1 inch above the highest jets, then turn it off. If the smell and hiss start and stop with the pump, the ozone generator is the source and nothing is wrong.
  2. Compare what you hear with normal sounds your walk-in tub makes, where the ozone hum is described.
  3. Remember that ozone only sanitizes the hydro lines. It does not replace the monthly flush of 2 cups of white vinegar and 2 cups of water, added to a tub filled 1 inch above the highest jets and run for 10 minutes.
  4. If you decide to disconnect it, follow ozone generator disconnect and service. Locate the T connection between the hydro pump and the ozone cord under the tub, unplug both ends of the T, tie the ozone cord to the frame, and plug the hydro pump directly into the plug from the control box.
  5. Test the hydro pump again after reconnecting to confirm it starts and stops normally.
Disconnecting the Ozone Generator
Chapters in this video
  1. 0:00 Locate The Ozone Generator We show you how to locate the ozone generator and its power cord in your walk-in tub.
  2. 0:15 Disconnect The Ozone Generator We demonstrate how to disconnect the ozone generator cord from the hydro pump and secure it within the tub's frame.
  3. 0:30 Ozone Generator Disconnected Your ozone generator is now safely disconnected from your Ella's Bubbles walk-in tub.

The video locates the ozone power cord and the T connection joining the hydro pump and the generator, disconnects both ends of the T, cable ties the ozone cord to the tub frame, and plugs the hydro pump directly into the control box plug. Watch: Ell'as Bubbles: Disconnecting The Ozone Generator with a full transcript.

When to Open a Ticket

If the smell is strong enough to be unpleasant, it continues after the hydro pump stops, or you hear a loud rattle rather than a light hum, send a short video with sound, a photo of the generator and its T connection under the tub, and your order details to your Ella dealer or the team at ellasbubbles.com/support or (800) 480-6850. The team confirms from your photos whether the generator is behaving normally.

Common Questions

Is the ozone from my tub safe to breathe?
The generator is a small, low output unit rated 0.04A that sanitizes the water in the hydro lines only while the pump runs. If the smell bothers you or you have a health concern, the generator can be disconnected without affecting the hydro massage.
Can the ozone system be turned off?
There is no separate switch to turn off the ozone sanitation system because it runs automatically whenever the hydro pump runs. To turn it off, you can disconnect the ozone generator by locating the T connection between the hydro pump and the ozone cord under the tub, unplugging both ends of the T, tying the ozone cord to the frame, and plugging the hydro pump directly into the plug from the control box. You can find detailed instructions and a video in the guide Disconnecting or Servicing the Ozone Generator on Your Walk-in Tub.
Why does my ozone generator make a hissing noise?
A light hum or hiss from the ozone generator is normal whenever the hydro pump is running. This sound is expected from the small generator unit, which is rated at 0.04A. The hum or hiss should stop when the hydro pump stops, confirming that the ozone generator is the source and functioning as intended. You can compare what you hear with other normal sounds your walk-in tub makes in the guide Hums, Clicks, Whooshes and Buzzes: The Sounds an Ella Walk-In Tub Makes and Which Ones Are Normal.
Does my 3 year old tub have an ozone system?
Ozone sanitation systems exist only on tubs with hydro jets, so if your 3-year-old tub has hydro jets, it includes an ozone system unless it has been disconnected. The ozone system runs automatically with the hydro pump to sanitize the hydro jet lines against mold and scum. To confirm if your specific tub has an ozone generator, you can provide your order details and a photo from under the tub to the support team.
Is there an ozone concentration table I can look at?
The published tub documents do not include a concentration table for the generator. What is documented is its 0.04A rating and that it runs only with the hydro pump; contact the team if you need more detail for your unit.

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.

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