Hot Tub Manufacturing – What to Look for in a Hot Tub


Acrylic is the most common spa shell material, but roto-cast polymer, vinyl and wood are also options. The spa shell not only determines the look of the hot tub, but also its cost, insulation, and strength.

Acrylic Shell

Acrylic is beautiful, durable, and versatile. Molds form it into contoured shapes for comfortable, form-fitting seating in a range of sizes. Supported by a frame, a wood or synthetic cabinet surrounds the spa. The equipment is completely contained within the surround.

Acrylic hot tub prices vary from a few grand to over $15,000, but high prices don’t mean high value.

Resin Unicast Hot Tubs

Built to last, molded resin spas are built with the shell and cabinet as one piece. This creates a strong, durable spa with an eye catching, easy care finish. Resin spas share some features of acrylic, like loungers and lighting packages, with fewer jets and a lower price.

Not all resin hot tubs are created equally. Some spa brands cut corners by heating the spa with the pump, rather than a dedicated heater. These spas do not heat as fast as spas with efficient heating element systems. Their temperature is difficult to regulate in very hot or cold weather.

Vinyl Soft Tubs & Blow-Up Spas

The vinyl hot tub is a low cost option with very few features. There are two types of vinyl spa: the cheap inflatable and the more expensive soft-sided spa.

Inflatable hot tubs are a short-term option for those looking to have a hot tub for one to two seasons. With just bubbles and no real massage action, don’t expect much more than a blow-up kiddy pool.

Soft-sided vinyl hot tubs are true portable spas. The shell and cabinet is replaced with vinyl and foam over a frame. These small hot tubs have no real seating other than the floor itself. Jetting is minimal, and the feature set is meager.

Equipment, Features and Options

With a size and material type in mind, learn more about the details. Get more of what you want out of a spa – without wasting money on sales ploys and marketing hype.


Vigorous jets that mix water and air give the best massage. Don’t fall for high jet counts and hokey massage packs that are hard or costly to replace.

Adding too many jets leads to decreased pressure. Adding larger, energy wasting motors is the only way to solve this pressure loss. Spa designs like this are not efficient, and can cost up to $100 in extra energy per month.


Spa pumps provide flow to the jets. More horsepower and more pumps don’t always mean a better massage or a better hot tub. A spa with outrageous total horsepower ratings or too many pumps (we’ve seen spas with 6!) will consume enormous amounts of energy. 

The ideal spa will have a good jet to horsepower ratio for ideal efficiency and jet strength.


Spa covers are not an option, they are a necessity. Heat rises, and a quality cover will conserve energy and save money on power bills. Locking straps protect the hot tub from dirt, weather and unwanted visitors.

Stereo, Lighting and Water Features

You don’t need color lighting systems, water features or audio in a spa. Still, these options can make your soak better and be a fun addition to a hot tub party. If you are thinking of adding these options, shop around before you pay thousands extra!

Spa dealers charge huge amounts – in the thousands – on top of already high prices for added options. Some companies offer optional Bluetooth audio, interior and exterior color LEDs and lighted water features.


Also called bubblers, these motors push air into the water through ports in the spa, creating champagne like bubbles. Although some enjoy this feeling, we do not recommend air blowers. Blowers pump cold air into the water, lowering the water temp and wasting energy. They can also be quite loud.

The best spas have jets that mix air and water without the need for a separate blower motor. These spa designs draw waste heat from the equipment bay, further saving energy dollars.


Filtration is an important part of keeping your water crystal clear. Well-kept, clean filters remove large particles from the water. This protects parts from damage, and improves water clarity. Filters should be replaced yearly for best results.

New hot tubs should include filters with advanced blue filter media. This blue media prevents bacteria and other microbe growth on the filter. Microbe resistant filters have more effective filtration, less odor, and are easier to clean.

One or two filters, depending on the spa size and number of pumps, are sufficient. Some spas use 3, 4 or even 5 filters, complicated or multi-part filters. Remember this adds to the long-term cost of the hot tub.


Full-foam spas fill the entire cabinet with spray foam insulation. This makes future repairs more difficult and wastes heat created by the pumps.

Roto-molded spas need some foam to support the structure. For acrylic spas, insulated cabinets with air space that captures heat from the pump motor is a better choice.

Most of a hot tub’s heat loss is through the top, not the sides, since heat rises. Like our homes, we insulate the floor, walls and the attic, to create a warm pocket inside.

The most energy efficient hot tubs have reflective backed foam insulation. Reflective foam acts like a mirror to bounce radiant heat back into the spa.

Spas with insulated bases prevent the cold ground from soaking up the heat in the cabinet. This extra protection can cut annual heating costs up to 20%. As an added benefit, an insulated base will keep moisture and vermin out of the hot tub cabinet.

Warranty and Support

Almost all new spas have warranties, but just having one isn’t enough if the service doesn’t back it up. Warranty service is tough if the dealer is not willing or able to help arrange it. If the dealer goes out of business, you may not receive warranty service at all.

A big box store that doesn’t specialize in hot tubs won’t be able to assist you with expert support. Once the warranty is expired, you are on your own.

Price vs. Cost

Now that you have an idea about what size, features and options you’d like, let’s talk about pricing.

Price is how much you pay for the tub itself. The true cost includes more: site prep, accessories, chemicals, and most importantly, power bills and repair costs. Subpar insulation, thin spa covers, cheap parts, and poor quality add to the lifetime cost of your spa.

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toddler floating in hot tubfeet splashing in the hot tub water