Frequently Asked Questions

Cold Plunge Tubs & Chillers

Alaskan Cold Plunge Tub

This will depend on whether you are using the tub with a chiller or as a standalone and whether or not you are treating the water with sanitizer.

If the tub is used without a chiller (i.e. ice cooling) and without a sanitizer like bromine, then we recommend changing the water after each session.

If you are not using a chiller, but you are using bromine and oxidizer, then your water may last 7 days or so. Although this varies depending on how often you use the tub.

If the tub is used with a chiller, the chiller’s pump and filter will circulate and clean the water, so you can change the water less frequently. If you are using a chiller and bromine/oxidizer we recommend changing the water every 2 weeks depending on how frequently you use the tub. The more frequently you use the tub, the more often you should change the water.

The tub has a diameter of ~31 inches and is ~40 inches tall. Filled to the brim it can hold approximately 130 gallons of water.

The plunge tub’s dry weight is 250lbs. Filling with water will add an additional ~1,100 lbs. Your foundation must be strong enough to support the full weight of the tub (~1,350 lbs).

We recommend placing the tub on a concrete pad or wooden deck that is engineered to support the weight of the filled tub.

We do not recommend placing the tub directly on dirt as it can sink into the ground due to the weight.

We do recommend treating the wood because this wood will be getting wet quite a lot. It’s normal for water to splash out of the tub during use. Also condensation can form on the inside of the tub lid. For your convenience, we pretreat the thermowood with a coat of linseed oil that will provide protection for about 12 months or so. After a year, we recommend treating the wood exterior of the tub, the stairs and both sides of the lid with a marine-grade sealer, such as SEAL-ONCE®. If you prefer to continue with an all-natural solution you can continue using a linseed oil treatment, however this will need to be applied every year or so.

Warranty terms for all products are available at:

No, the wooden cover is sold separately.

The tub is lined with reflective insulation which sits between the fibreglass liner and the thermowood exterior. This layer of insulation combined with the thickness of the thermowood cladding gives our cold plunges great insulation.

How fast the tub loses or gains heat largely depends on the external temperature. If there is a big temperature difference between your tub and the outdoor air, it will heat up faster.

The bromine kit and water balancing kit serve different purposes, and both are required to keep your water clean if you plan on changing your water infrequently.

The bromine kit is used to keep the water sanitary. This is required to keep your water free of bacteria that can cause itchiness, pink eye, and other conditions associated with pool use.

The water balancing kit is used to keep your water with an acceptable pH, alkaline, and hardness level. If your water’s levels get out of balance, it will damage your chiller equipment.

Any damage to the chiller or plunge tub due to improper water maintenance is not covered under Redwood Outdoor’s product warranty or 3rd party equipment warranties.

When testing your water, the water should be tested at room temperature. The best way to test cold plunge water is to take a small sample in a cup. Allow the cup to sit indoors for a couple of hours and then test it as normal.

If you change your water frequently (e.g. after each use), your water will be naturally clean and the use of chemicals is likely not required.

On our newer Alaskan tubs (from mid 2023) chiller hoses can connect to the cold plunge tub via 3 pre-plumbed wall-fittings. There are 2 lower wall-fittings for dual suction and a high wall-fitting for the return flow.

All our wall fittings are 1/2" MPT. Our chiller hoses have a 1/2" FPT end.

Prior to mid 2023, our tubs were not pre-plumbed. So hoses were designed to be hung over the side of the tub body. The inlet hoses needed to be fully submerged, however, the outlet hose could hang above the surface of the water.

Yes, the hoses are rigid and can support the lid. The lid will partially ajar if you put the cover over the top of the tub while the hoses are inserted. This is not a problem.

You can drill the wooden lid to create an opening for the hoses, however, we do not recommend drilling through the sidewall of the tub. If you puncture the sidewall or liner of the tub, you may experience leaks and your product warranty will be voided.

If you live in climate with freezing conditions, you need to ensure that the water in your tub does not freeze . If the water in your tub freezes and expands it can damage and crack the liner (just like an exploded bottle left in the freezer). Damage from freezing is not covered under warranty.

To prevent your tub from freezing there are several options: (1) If you purchased the Deluxe Chiller then this should be running at all times during freezing conditions. This will circulate and heat the water to prevent freezing. (2) You can use a stock tank heater in the tub while it's not in use. A 1000W stock tank heater costs about $50 and will plug into a 110V outlet. Make sure the outlet is GFCI protected and do not use an extension cord for the connection. (3) Drain the tub.

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