The stove must never be lit unless the water is at the fill line marked on the tub, or at least 4 inches above the chimney collar, and the water must stay at that level the entire time the firebox is hot. Firing the stove with inadequate water can cause physical damage to the firebox, chimney and firebox fence, and poses a real safety hazard. This can't happen if the water level is sufficient, so please follow the manual instructions carefully and ensure everyone with access to your tub does the same before every fire, especially after refilling or draining. Newer models are built with a fill-line marking and a QR code on the firebox lid. On older tubs without that marker, measure at least 4 inches above the chimney collar instead. Never drain below that level until the firebox has fully cooled. With proper water level maintained, the firebox is built to last 15+ years.

Welding can be attempted, but replacement is the more reliable fix. Pinhole leaks are usually caused by firing the firebox with insufficient water, or by rainwater mixing with ashes inside it. Prevent this by keeping the storage cover on whenever the tub won't be used for an extended stretch.

Likely condensation, or a chimney cap that isn't intact or properly seated. Check that first.

This can happen with certain wood types or from incomplete combustion. A professional chimney sweep can clear it; no special precautions are needed beyond protecting the aluminum from abrasive tools.

On the electric units, the bottom fitting that the PVC connects to is aluminum and protrudes past the cedar cladding, so a ground clamp installs easily right onto it, bonding the tub's aluminum structure itself rather than relying on the plumbing lines. Use an aluminum ground clamp sized to your grounding conductor. If your electrician would like the exact fitting dimensions or a specific clamp recommendation for their conductor size, email hi@alumitubs.com and we'll confirm the details.

Check that the black collar is fully tightened and that the O-ring is present and seated correctly. If the collar itself is cracked or broken rather than just loose, see the replacement heater connection collar above.

That's the pump cord. It plugs into the control/heater box at the blue, rubberized, watertight connector. Reconnect it there and you're all set.

Ensure the four black ring gaskets are installed at the end of each hose connection and threaded connections are secured with teflon tape.

If a power outage occurs and there's a power surge when power returns, it can blow a fuse in your system. If your system stops working after an outage, check the fuses inside the control panel with the power off. Look for a fuse that's turned black, shows a burn mark, or has a broken wire inside it. If you find one, a fuse replacement will get the system operational again.

Email hi@alumitubs.com for a replacement:

• F3 heater fuse, part #24514 for a 240V heater, or part #26982 for 120V.
• F4 and F5 board protection fuses, part #26983.

This typically points to a fault at the heater connection or moisture getting into the electrical components, not an issue with your home's wiring, especially if the tub is on its own dedicated breaker. Don't run additional heating cycles unattended until it's been looked at. Email hi@alumitubs.com for support.

If you're seeing this pattern, the system powers on and starts priming normally, the pump runs and the heater engages, but after a few seconds to a minute circulation stops and the heater shuts off, the system re-enters a purge cycle or shows a flow/heater error, the displayed temperature jumps by a few degrees without the water actually changing temperature, and/or the jets start and stop inconsistently, and you've already confirmed the water level, both black equipment valves are open, bled the filter canister, tried a new filter, and power-cycled at the breaker, this usually points to a relay in the control board rather than trapped air. Reach out to hi@alumitubs.com, as a replacement board is a straightforward swap.

First bleed the air out of the filter canister with the power off. To do so, open the air release knob on the filter canister until water flows out steadily, then close it and power the unit back on. If the short-cycling continues after that, it likely points to the control board and is worth a support email to hi@alumitubs.com.

This triggers if wood heat pushes the water temperature above 108°F on a Hybrid unit. This is inside the control box, so you'll need to flip down the cover (see the diagram in the manual for the dip switch location). While the power is on, move dip switch 1 to the ON position. Wait one minute and see if the error code clears. If it clears, turn the power off to the system, turn dip switch 1 off, then power the system back on. Everything should be back to normal.

Email hi@alumitubs.com and we'll send a replacement touchpad.

If the touchpad is working and displaying normally but the water isn't heating, this can point to the heating coil (heater element, tube, and sensors) rather than the control board. Email hi@alumitubs.com with your address and we'll get a replacement heating coil assembly sent out.

Download the ControlMySpa app (iOS or Android), open Setup, confirm Bluetooth is on, and stand within about 10 feet of your tub with it powered on. The app will detect your WiFi module via Bluetooth. Confirm the serial number shown matches the one printed on the back of the module, then enter your CMS code (provided with your tub) to finish setup. The app will only be able to connect to the tub in the first 10 minutes that it's powered on.

First, double-check that the serial number on the WiFi module matches what's shown in the app during setup, as a mismatch is the most common cause. Also check that IPv6 is disabled on your home WiFi network, as this can prevent the module from connecting. You can also read the module's status light for a quick diagnosis:

• Solid red, not connected to the tub's system at all.
• Blinking red, connected to your home network, but not talking to the tub's control board.
• Blinking green, connected to the tub, but no internet connection (check your home router).
• Solid green, everything's working.

If the serial numbers don't match, or the light suggests the module itself isn't communicating, email hi@alumitubs.com for a replacement.

The ballast has its own status light. Solid green means it's powered and running normally, and this should always be lit whenever the system has power. Solid red means the UV-C lamp itself is actively on. If you're not seeing green at all, it's a power or connection issue rather than a bulb problem.

Clean the quartz tube every 6 months.

In over twenty-five years of building AlumiTubs, we've found leaks trace back to one of three things: the tub froze with water left inside, the base isn't fully level and supported, or the firebox was lit without enough water in it (or the tub was drained while the firebox was still hot). All three are covered in your manual, and all three are fixable once identified.

• Froze with water inside: ice expanding inside the tub can pop the aluminum rivets holding the structure together, which shows up as a leak at a seam. See your manual's freeze prevention guidance for your system type.
• Base isn't level or fully supported: see below for the fix.
• Firebox lit with insufficient water, or drained while still hot: see Firebox Issues above.

Not sure which applies? Send a few photos or a short video of where it's leaking to hi@alumitubs.com and we'll help you pin it down.

Marine-grade aluminum can develop surface changes from electrochemical reactions combined with imbalanced water chemistry or hard/soft water extremes. This is cosmetic, not structural.

Before considering any refinishing, there are two things worth trying first, since minerals in your fill water (like copper or iron) are a common cause: a hose filter when filling the tub (a PreFresh Hose Filter is a good option), and a descaling product like Spa Scale Defender, since minerals are sometimes left behind in filters and crevices even after a fresh fill, and a descaler can help clear the source.

• Tubs built after June 2026 have a marine-grade protective barrier built in at the aluminum surface, and are safe with all approved treatment methods.
• For tubs built before June 2026: email hi@alumitubs.com and we'll help you restore the surface and reapply the marine-grade protective barrier to prevent recurrence, along with support on water chemistry and electrochemical balancing.

The most important thing is keeping your water balanced and in range. A helpful property of aluminum is that it forms its own protective oxide layer, so if you balance the water right away when filling (a hose filter helps) and keep it in range, there is no further degradation of the material. If you do notice surface changes, the first question is usually how long the water has been sitting, since water left too long or out of range is the main cause. See "I'm seeing surface changes" above for restoring the surface.

This applies to seam sealant. Clean the area with lacquer thinner or acetone, remove the old sealant with a putty knife, and reapply SikaFlex. Note: this seam sealant is a separate product from the protective barrier on the aluminum interior, so use the right process for the right surface (see below).

This is likely due to the tub not being fully supported, causing a hairline crack in the sealant. Resolve this by fully supporting the tub, then reapplying a heavy bead of sealant 1ft in each direction of the leak, pressing and smoothing it with a gloved finger, and letting it cure for 24 hours.

Check the drain kit connection first and reseal at the base outlet if needed. Most post-move leaks trace back to the drain fitting needing to be re-threaded after the tub was dismantled and rebuilt on a new platform.

Corrosion or wear at the drain fitting comes from introducing other metals (metal-to-metal). The fix is to use the spec'd boat plug, which has a rubber casing that seals the fitting and prevents leaking or further degradation, rather than a metal-to-metal plug. The same fitting has run tubs for decades with no issues when the correct plug is used. If a leak persists after switching to the boat plug, it is usually lower down in the treads. See the drain plug options in Replacement Parts above, and email hi@alumitubs.com if you'd like us to send the proper plug.

With the stove at the back (12 o'clock), we install the external drain flanges at 9 o'clock by default, but they can be placed anywhere between 3 and 9 o'clock. We don't install them any closer to the stove, to prevent injury.

This is moisture in the wood. Use a longer fastener to bridge it until the boards dry out and shrink back to size. A 5" 1/4-20 Phillips pan-head machine screw works well as a temporary fastener (the Amazon "Hard-to-Find Fastener 014973480387, 1/4-20 x 5" is one source). Once the wood has dried, the standard hardware fits again.

Four screws hold the fence to the stove, so remove those to take the fence off. Then remove the screws that hold the fence itself together (Robertson #2 bit). Clean the wood with an oxygen bleach and a soft brush. Avoid abrasive tools near the aluminum.

This is a different process from the seam sealant above. The interior carries a marine-grade protective barrier at the aluminum surface, and refreshing it uses a specific product and steps, so we set each owner up directly rather than publish a generic recipe here.

1. Clean the area first. Wash with a high-volume hose and a mild pH-neutral soap. Don't use a pressure washer, shop air, or solvent cleaners, as these can damage the surface. Let it dry completely.
2. Inspect for chips, scratches, or surface changes.
3. Email hi@alumitubs.com and we'll send the correct product and the full application steps for your tub, including the cure time and temperature guidance.

Use Thompson's Water Seal (clear wood sealer). This is best applied before installation so all sides of the cedar can be coated evenly.