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 fibreglass

The mainstream option. Moulded 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. 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 sanitise 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.

Rotomoulded 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 moulded 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. It can be relocated across a property or taken with you.

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. It's backed by a 25 year structural warranty.

Tradeoffs, stated plainly: aluminum is a metal, and several sanitisers 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.

How we protect the aluminum.

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	Rotomoulded
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.