Can Mold Grow Inside the Air or Hydro Lines of a Walk-In Tub?

Water that is left sitting inside a tub's lines can grow mold and mildew, and Ella walk-in tubs are built around preventing exactly that. On the air side, the Auto Purge cycle blows the air lines dry on its own after every air bath, and on the hydro side, ozone sterilization on tubs equipped with it and a simple monthly vinegar flush keep the pump lines clean. Walk-In Tub Therapy Options and Features lists the jetting systems these lines belong to; this page explains where water collects, what each defense does, and what to do if you see flakes or smell mildew.

Where Water Sits After a Bath

An Ella tub with jets has two separate networks under the deck. The hydro massage pushes bath water through a pump and out of the hydro jets, so the hydro lines carry whatever is in the water, including body oils, soap film and bath product residue. The air massage uses a blower to push air through small air jets in the seat, at the base of the seat and in the footwell, and after an air bath some water naturally flows back into that air piping. If either kind of moisture were left in place for weeks, it could develop a film, and that film is where mildew and bacteria start.

The video on this page takes you behind the bathtub for a look at those lines. It shows how many tubes and lines run under a single tub, how neatly they are bundled, the consistent glue joints, and the grounding straps on every component. The narrator makes the point that matters here: with that many lines, the Auto Purge system is important because it blows them out so that mold, mildew and bacteria cannot grow inside, and you can get into the tub next time knowing the lines are clean and dry.

Auto Purge Keeps the Air Lines Dry

Every Ella tub with air massage has Auto Purge, a self-cleaning cycle that expels residual moisture from the air lines to prevent mildew and mold. It is entirely automatic and the timing is fixed, as How Long Does Auto Purge Run After a Bath and Can I Change It? details.

• The cycle starts about 20 minutes after the air pump is switched off. The countdown begins at shutoff, so if you test the air for a moment before a bath, the clock restarts from that shutoff.
• The blower runs for 120 seconds, pushing the water that drained back into the air piping out through the air jets, then stops on its own.
• There is no button, timer or setting for it. It cannot be shortened, delayed or cancelled once it begins, and it runs whether the tub is full, empty, or you are still sitting in it.
• The only thing that prevents a purge is a lack of power. Switching the tub's breakers off after every bath would stop the cycle, and that is a poor habit, because the water in the air piping would then sit there.

When the purge fires while you are still in the tub, the air feels cool for two minutes and then stops. Nothing is wrong. If you would rather get out, drain and exit normally while it runs. The burst of air you hear 20 minutes after your bath is one of the normal sounds described in Hums, Clicks, Whooshes and Buzzes: The Sounds an Ella Walk-In Tub Makes and Which Ones Are Normal, and so is the light hum of the ozone generator covered next.

Ozone and the Vinegar Flush Keep the Hydro Lines Clean

The hydro lines are not blown dry by Auto Purge, so they rely on two other measures. The first is ozone sterilization, an available feature that is part of the hydro massage system. On tubs equipped with it, the ozone generator starts and stops with the hydro pump, sanitizing the water system every time you use the hydro massage, and it makes a light hum when it is running by itself.

The second is the monthly vinegar flush, which is the owner's part of the job and the same procedure used before first use. Combine 2 cups of white vinegar with 2 cups of water, fill the tub with water to one inch above the highest jets, add the mixture, run the tub for 10 minutes, then drain. Flushing after every bath is not necessary. A few habits support the flush:

• Remove and clean the pump inlet cover of hair and debris each month, then wipe it with a non abrasive towel.
• Set aside oils, bath beads, bubble bath and bath bombs. These feed the buildup inside the lines and can clog jets.
• If the tub has sat unused for a while, flush and drain the pump circulation system before the next bath instead of waiting for the monthly date.

What Black Flakes or a Musty Smell Actually Mean

Owners who worry about mold usually do so because dark specks or brown slime appeared when the jets ran. That material is almost always body oils, soap film and bath product residue that collected in the plumbing, now being loosened and pushed out. A tub that sat unused can also release a film that formed in the lines as dark specks. The fix is the vinegar flush, repeated until the drained water runs clear, and the deeper checklist is in Why Do Black Flakes or Slime Come Out of My Tub Jets?.

1. Run the flush exactly as described above.
2. Look at the drained water. If it still carries flakes or a dark film, refill and run the flush again, and keep repeating until the water runs clear.
3. Clean the pump inlet cover and wipe the shell with mild dish soap or a 1 to 1 vinegar and water mix on a soft cloth.
4. Review what goes into the bath water and return to the monthly schedule.

If the flakes keep returning after repeated flushes, or you notice a persistent mildew smell around the drain or pump area, contact your Ella dealer or the team at (800) 480-6850, or open a request at ellasbubbles.com/support. Include your model, a photo of the debris in the drained water, and a note on how often the tub is used and how long it has been since the last flush. With the air lines purged automatically after each air bath, the hydro lines sanitized by ozone where fitted, and the monthly flush done, there is no standing water for mold to live in.

Watch: Inside the Build: Under-the-Deck Piping of Our Walk-In Tubs | Voted Safest 2020 | Ella’s Bubbles with chapters and a full transcript.

Related Guides

• Black Flakes, Brown Slime, or Debris Coming From the Jets: Cleaning Steps That Work
• What is ozone sanitation, and is the light humming noise from my tub normal?
• Before Your First Bath: The Initial Vinegar Flush and First-Use Checklist

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