Hot Tub Materials Compared
Most hot tub material comparisons are written by someone who sells one of the materials. This one is too, so read it with that in mind. We've tried to state the tradeoffs we'd want stated if we were the ones buying.
Acrylic over fiberglass
The mainstream option. Molded acrylic, insulated cabinet, jets.
Strengths: forgiving on water chemistry, since the acrylic is chemically inert. Widely serviced. Chlorine and salt systems work fine.
Tradeoffs: the acrylic is a petrochemical product and you're soaking in it at temperature. Heavy, typically 700 to 1,000 lbs empty, and effectively unmovable once sited. The working parts sit behind sealed panels and packed foam, awkward to reach and sometimes impossible. Multiple jets and long internal plumbing runs give water places to sit between soaks, which is where biofilm forms, and it is why most acrylic spas are sold with UV or ozone to bring sanitizer demand back down. Cabinet and frame are the usual failure point rather than the acrylic itself. Not recyclable, and disposal is genuinely difficult.
Traditional all cedar
The classic. Staves held with steel bands, sealed by the wood swelling.
Strengths: beautiful, natural, no synthetic material against the water. Repairable stave by stave.
Tradeoffs: it is sensitive to water exposure in both directions. The seal exists only because the wood is swollen, so the tub generally has to stay filled. Let it dry out and the staves contract, and you get leaks and cracking when it swells again. That makes it a poor fit for a seasonal cabin, a rental with gaps between bookings, or anywhere with a hard freeze.
It also arrives as a kit rather than a tub, so it has to be assembled on site, and once assembled and swollen it is effectively fixed in place. Moving it means taking it apart.
Wood in permanent contact with warm water eventually degrades, and service life is shorter than the alternatives. Cedar is porous, so it is genuinely harder to keep clean and harder to sanitize than a smooth surface. The steel bands are a corrosion point of their own. And there is no insulation in the walls, so heat loss is higher and heat up times are longer, particularly in cold weather.
Rotomolded plastic
The budget end. Single piece polyethylene.
Strengths: cheap, light, effectively indestructible in normal use.
Tradeoffs: looks it. Limited lifespan under UV. Not repairable, not recyclable in most municipalities.
Aluminum lined cedar
What we build. Marine grade aluminum structure, cedar exterior, made on the Sunshine Coast since 2001.
Strengths: the water sits against protected metal, not plastic or porous wood. It doesn't rely on swelling to stay watertight, so it can be left empty over a winter or between bookings without leaking or cracking, and it isn't climate sensitive. It doesn't crack or delaminate the way molded acrylic does.
It arrives pre assembled rather than as a kit, and it's built with 360 degrees of insulation, so heat goes into the water and stays there. Light enough to move at 200 lbs empty for the Small, 220 for the Standard and 300 for the Large, so it can go where a 900 lb acrylic spa can't, and it stays moveable afterwards.
Nothing is buried. The cedar, the firebox, the heater, pump, board and filtration are all bolted, banded or slotted onto the aluminum structure, so any of them can be reached and replaced by hand. You can change heating system entirely as your property and plans change. We still supply parts for tubs built two decades ago, which is what a 25 year structural warranty actually rests on.
No UV or ozone required. We could sell you a UV system. Most spa brands do. The truth is you don't need one. UV and ozone exist to reduce how much sanitizer a spa needs, and they exist because jets, internal plumbing and packed foam give water places to sit where biofilm forms. In an AlumiTub, water sits in a smooth aluminum vessel with a simple filter circuit, and everything it touches can be reached and cleaned by hand. Keep the water in range and sanitizer demand stays low on its own, which is the outcome UV was there to produce. One less thing in the circuit, and one less thing to replace.
Tradeoffs, stated plainly: aluminum is a metal, and several sanitizers that are standard for acrylic spas aren't compatible. No chlorine, no salt systems, no copper or silver products. Bromine, hydrogen peroxide and plant derived treatments are what work, and calcium hardness needs to sit in a defined range.
That's less of an obstacle than it sounds, because we don't leave owners to work it out. Good Clean Living Water Care is a curated collection built specifically around aluminum and around our published ranges: fill purification, balancers, a monthly plant derived stabilizer, filter care, and a deep clean every 3 to 4 months. Everything in it is compatible by design, so water care is a routine rather than a research project.
What has also changed is that the tub no longer depends on the owner getting everything right. Every AlumiTub is built with built-in protection at the aluminum surface, and anodes ship with every system that specifies them. We still publish water care ranges, because balanced water protects the equipment, the cedar and the quality of your soak, not only the structure. The difference is that the tub is built to handle a mistake.
Choosing
| If you want | Look at |
|---|---|
| Chlorine convenience above all | Acrylic |
| A natural material, and you'll keep it filled year round | Traditional cedar |
| Lowest cost, don't care how it looks | Rotomolded |
| 360 degrees of insulation, flexible heating options, portability and replaceable components | Aluminum lined cedar |
If you want a straight answer about whether an aluminum tub suits your water and your property, email hi@alumitubs.com with your location and water source. We'd rather talk someone out of the wrong build than sell the wrong one.
Common questions
What is the best material for a hot tub?
It depends on what you value. Acrylic is the most forgiving on water chemistry but heavy, unmovable, and difficult to dispose of. Traditional all cedar is beautiful but the seal depends on the wood staying swollen, so it generally has to stay filled or it leaks and cracks, it arrives as a kit to assemble on site, it cannot be moved once assembled, it is porous and harder to keep clean, and the walls are uninsulated. Rotomolded plastic is cheap and durable but has a limited lifespan under UV. Aluminum lined cedar stays watertight when left empty, arrives pre assembled with 360 degrees of insulation, offers wood fired, electric or hybrid heating that can be changed later, and has replaceable components, but needs a compatible sanitizer and calcium hardness within a defined range.
Why do hot tubs need UV or ozone, and does an aluminum hot tub need it?
UV and ozone exist to reduce how much sanitizer a spa needs. They are common on acrylic spas because multiple jets, long internal plumbing runs and packed foam give water places to sit between soaks, where biofilm forms and sanitizer demand climbs. In an AlumiTub the water sits in a smooth aluminum vessel with a simple filter circuit, and everything it touches can be reached and cleaned by hand, so demand stays low on its own once the water is in range. UV also breaks bromine down as water passes through it, and bromine is what an aluminum interior requires, so the two work against each other.
Is an aluminum hot tub better than a traditional cedar hot tub?
An aluminum lined tub does not rely on the wood swelling to stay watertight, so it can be left empty over a winter or between bookings without leaking or cracking, and the cedar is not in permanent contact with warm water. It also arrives pre assembled rather than as a kit, is insulated on all sides, and stays moveable. The tradeoff is that aluminum is a metal, so chlorine, salt chlorine generators and copper or silver based products are not compatible, and calcium hardness needs to sit between 150 and 250 ppm.
How much does an aluminum hot tub weigh?
Empty weights are 200 lbs for the Small, 220 lbs for the Standard and 300 lbs for the Large, compared with 700 to 1,000 lbs for a typical acrylic spa. That is light enough to roll into place by hand and light enough to move with you.