If you want a hot tub that is 100% free of plastic, choose a Snorkel wood fired tub. The wood that surrounds you is western red cedar. Our aluminum submersible wood stove heats a hot tub like this at 30F/hr. The snorkel is the air slot that pulls the air under the water to burn the wood clean at 1000 F and out the chimney. Damper and air intake control keeps you in control. No plastic and simple. Customers sometimes get 40 years out of their set up. for details.