There is no published metric to imperial crossover for the small air hoses on an Ella walk-in tub, so the tubing is matched to your tub by serial number rather than by reading a size off the old hose. The current push button air hose is PVC tubing with a 1/8 inch inside diameter and a 1/4 inch outside diameter, while some older tubs used a polyurethane tube at 1/4 inch inside by 3/8 inch outside, and Ella ships the right one with its connectors under the lifetime parts warranty. For the larger lines that feed the jets, How do I replace a damaged air line on my walk-in tub? covers how the line is identified before anything is cut.
Why the Hose Is Matched by Serial Number, Not by Eye
Tubing sizes on Ella tubs have changed over the years. The hose on a tub built in one period is PVC at 1/8 inch inside by 1/4 inch outside, and the hose on an older tub is polyurethane at 1/4 inch inside by 3/8 inch outside. Both look like a small tube under the deck, and a metric reading taken with a ruler can land between the two. Because Ella does not publish a crossover table, the team looks up your tub by serial number and matches the tubing to what was fitted at the factory.
The fit matters more on these hoses than on most plumbing. Ella push buttons are pneumatic: pressing the chrome button sends a puff of air down the small tube to a relay in the blue control box, and that puff is the only signal the box receives. A hose with the wrong inside diameter either will not go onto the nipple or will not grip it, and a hose that has lost its grip is the usual reason a pump or light simply stops responding, as Why Do the Little Air Hoses Keep Falling Off My Tub Controls? explains. A substitute that is close but not exact tends to reproduce the very fault you are trying to cure.
The Lines Under the Tub and the Sizes Ella Publishes
Several kinds of tubing run under an Ella walk-in tub, and they are not interchangeable. Before you measure anything, work out which line you are holding, because the small control hoses, the air jet lines and the hydro lines each take different tubing and different connectors.
| Line | Material | Size listed in the sources | Where it runs | How it is replaced |
|---|---|---|---|---|
| Current push button air hose | PVC | 1/8 inch inside, 1/4 inch outside | Chrome push button to the blue control box | Matched by serial number and shipped with connectors |
| Older push button air hose | Polyurethane | 1/4 inch inside, 3/8 inch outside | Same route on older tubs | Matched by serial number and shipped with connectors |
| Red tubing for the water push button | not listed | not listed | Hydro push button to the pump | Unscrew the nut at either end and fit the new tube onto the nipple, no cement |
| White corrugated air line and smaller rubber air lines | not listed | not listed | Air manifold out to groups of air jets | Cut out the hole and rejoin with a matching coupling, or replace the run if brittle |
| White PVC hydro line | PVC | 1/2 inch | Pump to the hydro jets | Cut out and splice with 1/2 inch couplings and PVC cement |
| Flex pipe | not listed | 1 inch | Hydro system | Spliced with 1 inch couplings and PVC cement |
| Vinyl tubing to the ozone check valve | Vinyl | 3/8 inch | Ozone check valve assembly | Replaced along with the check valve assembly if damaged |
What the table means for your repair is simple. Only the two push button hoses have a published inside and outside diameter, and even those depend on when your tub was built. Every other line is identified by the team from a photo or video rather than from a size, so the request you send is what gets the right part on the truck. If the hose you are replacing is one of the larger jet lines, How Do I Replace the Air Massage Line on My Walk-In Tub? covers splicing versus replacing the whole run, and if it turns out to be a hydro hose the parts are different again, as Damaged Hydro Jet Hoses, PVC Lines and Jet Fittings: What Can Be Replaced sets out.
What to Send so the Right Tubing Ships the First Time
- Photograph the tubing next to a ruler, so the team sees the size in the same frame as the hose.
- Photograph both ends where the hose connects, at the button and at the control box or manifold, so the connector style is visible.
- Note the total length you need, measured along the route the hose actually takes rather than straight across.
- Count the connectors you need by type: elbows, tees and straights.
- Add your model and serial number. The serial is on the label behind the magnetic access panel next to the door.
- For a jet line, record a short video with the air system running so the leak is visible.
Open a ticket at ellasbubbles.com/support or call (800) 480-6850 with that information. Replacement air tubing and connectors fall under the lifetime parts warranty once the team has confirmed the problem, and Ella supplies both the tubing and the connectors. Labor and any work needed to open access to the underside of the tub are not covered, so plan on your original installer or a local licensed plumber for the hands-on part. Ella does not send technicians.
The same route applies wherever the tub was installed. The hose is matched and supplied by Ella rather than bought locally, so there is no need to search hardware stores for an imperial size that stands in for a metric one. Tell the team where the tub is located when you open the ticket and they confirm shipping from there.
Fitting the New Hose so It Stays Put
On a push button hose, the fit is a twist-and-push onto the labeled nipple at the blue control box: Water to Pump #1 Airswitch, Air to Blower/Pump #2 Airswitch, Light to Light Airswitch. At the deck, work a fine flat screwdriver under the chrome collar, lift it off, remove the button and pull out the black core, then seat the hose on the nipple and snug the lock nut before reassembling. Give the hose slack, because a hose under tension works itself off no matter how well it is seated. After reconnecting, pull the hose off the box for a second so the line returns to room pressure, refit it and listen for the click inside the box when you press the button. The video on this page shows the control box and push control side by side, the twist-and-push at the nipple, and the chrome collar coming off so the lock nut behind the button can be reached.
On an air jet line, turn off the tub breakers and drain the tub, cut the tube on each side of the damage and push on a coupling that matches the tube, then restore power, run the air system and watch the joint for a few minutes. Let a purge cycle run and check again, since the auto purge blows residual water out of the lines about 20 minutes after the air pump is switched off and will reveal any joint that is not sealed. Air Line Leaking Under the Tub: Cut Out the Hole and Rejoin With a Coupling has the full sequence. On any glued hydro splice, keep cement off the inside of the line, because a blob inside a small line can block it.

Watch: How to Secure Air & Hydro Connections in Your Walk-In Tub | Ellas Bubbles with chapters and a full transcript.
Related Guides
- Who Replaces My Air Button and Hose If I Cannot Reach Under the Tub?
- Push-Button Air Hoses: Which Port on the Blue Box, Reconnecting a Hose That Pops Off, Red Hoses, Sealing and Replacing a Button