Most hot tub spec sheets are written to impress, not inform. They stack numbers, drop brand names you have never heard of, and use words like “premium” and “fully insulated” without explaining what either means in practice. This guide gives you a framework for reading them honestly. Use it at every showroom you visit. That includes ours.
Jet count: why “120 jets” tells you almost nothing
Jet count is the most-quoted number on any spec sheet and probably the least useful. A tub with 120 jets sounds better than one with 40. It rarely is.
What actually matters is jet placement, adjustability, and whether the jets are genuine hydrotherapy jets or decorative holes. A well-placed 40-jet tub, with deep tissue directional jets at the lumbar, neck, shoulders, and calf positions, will do more for your body than a 120-jet tub where eighty of the jets are small fixed nozzles that produce a general fizzing sensation around your thighs.
When you read a spec sheet, look for:
- Directional jets. These can be aimed at specific muscle groups. Fixed jets cannot.
- Adjustable flow. You should be able to open or close individual jets, not just dial down the whole pump.
- Seat-by-seat mapping. A good spec sheet will tell you what each seat is designed for: deep tissue, neck, foot, shoulder. A vague “120 jets” entry without a seating diagram should prompt questions.
- Jet brand. Waterway and CMP are the main jet manufacturers used by reputable builders. Unknown jet brands mean uncertain replacement availability in five years.
If you are in a showroom, ask the salesperson to sit you in the tub and point to each seat’s intended function. If they cannot do that, the tub was not designed with intent.
Insulation claims: what “fully insulated” actually means
“Fully insulated” can mean a layer of fibreglass mat over the shell, a modest foam fill, a reflective barrier, or a genuinely engineered thermal system. There is no industry standard definition. The phrase means as much as the manufacturer decides it means.
Here are the main approaches, from least to most effective:
- Partial foam. Foam is sprayed around the major plumbing only. The cabinet sides may have a thin sheet or nothing. Common on budget tubs. Running costs are noticeably higher.
- Reflective barrier systems. A foil layer reflects heat back toward the shell. Better than nothing. Less effective than full foam.
- Full foam. The entire cabinet cavity is filled with expanding polyurethane foam. The foam holds plumbing in place (reducing vibration and pipe movement), deters pests, and provides real thermal retention. This is what you want as a baseline.
- Full foam plus thermal blanket. Some manufacturers add a base pan with a thermal blanket beneath the floor of the tub. This catches the heat that would otherwise escape downward. Worth looking for.
Two examples of what real insulation looks like in practice: VitaSpa’s Northern Exposure system uses full foam combined with copper plumbing and Thinsulate wrapping, which addresses both heat loss and pipe freeze risk. VitaSpa’s HeatSave option adds a further thermal layer beneath the tub floor. These are the kinds of specifics to look for. When a manufacturer names and explains their insulation system, that is a sign they have thought about it. When they just write “premium insulation” in large type, ask them to explain what is behind the cabinet panel.
The question to ask any dealer: “Can you describe, step by step, what is between the water and the outside air?” If they cannot answer that clearly, the insulation probably does not warrant the description they gave it.
Frame material: what is underneath
The frame is the skeleton. It does not get shown in product photography, and it is rarely described in detail on spec sheets. It matters.
- Galvanised steel. This is what you want. Treated steel does not rot, does not warp, and supports the weight of a full tub of water and people for decades. Ask whether it is powder-coated or galvanised. Powder coating can chip and rust over time. Galvanised is more durable.
- Treated timber. Used by some manufacturers. Better than untreated, but wood in a humid environment will eventually move and eventually rot. The quality of the timber treatment varies considerably. Ask for specifics.
- Plastic strapping or composite framing. Used on some lower-priced tubs. Not inherently a dealbreaker, but worth knowing. Ask how the frame is constructed before you see the word “steel” and assume it refers to the main structure rather than a single reinforcing piece.
Controls: Balboa, Gecko, and why it matters
The control system is the brain of the tub. It runs the pumps, heater, lighting, and any smart features. Two brands dominate the reputable end of the market: Balboa and Gecko.
Balboa is the industry standard. It is in the majority of mid-range and premium tubs made by serious manufacturers. Parts are available through multiple suppliers. Engineers in the field know the system. If your Balboa board fails in eight years, you can get a replacement without drama.
Gecko is also a solid choice. Canadian-made, well-supported, used by several good manufacturers.
The concern is proprietary controls from manufacturers you have not heard of. These are systems built to a specific brand’s order, often by a third party, and sold only through that brand’s own service network. When the brand changes its supply chain, or exits the market, or simply loses interest in stocking old parts, you are left with a tub whose brain cannot be replaced. This is not hypothetical. It happens regularly enough that it is worth asking the question directly: “What control system does this tub use, and who manufactures it?”
If the answer is a brand name you cannot find independently online, take note.
Shell material: acrylic versus rotomoulded plastic
The shell is what you sit in and look at. Two main materials are used:
Acrylic. This is the standard for any tub above the entry level. Acrylic shells are formed under heat and pressure, then backed with fibreglass for strength. The two main suppliers of acrylic sheet to hot tub manufacturers are Lucite and Aristech. Both produce durable, repairable material. If an acrylic shell cracks or chips, a skilled technician can repair it. The surface is non-porous and holds up well against chemicals and UV exposure over many years.
Rotomoulded plastic. This is a one-piece moulded plastic shell. Less expensive to produce. Used on some entry-level tubs and inflatable alternatives. The surface is more porous than acrylic, more susceptible to UV fading, and harder to repair cleanly if damaged. If you are looking at a tub under £3,000 and the shell material is not specified clearly, this is likely what you are getting.
The spec sheet should state the shell material. If it does not, ask. If the answer is vague, treat that as information.
“Made in Britain”: what it sometimes means
Several UK brands carry a “Made in Britain” badge or similar wording. Some earn it. Some are applying it to a product that was manufactured in China and assembled, or finished, in the UK.
Assembly in the UK is not nothing. It means local quality control, potentially better pre-delivery preparation, and a shorter supply chain. But it is not the same as UK manufacturing, and the distinction matters when you are paying a premium on that basis.
VitaSpa tubs are manufactured in the United States. That is documented and consistent. Reef Spas is transparent about its supply chain in a way that is worth reading directly if you are considering one of their models. The honest answer from any dealer is: “Here is where the shell is made, here is where the frame is made, and here is where it is assembled.” If you get a flag and a slogan instead of that answer, push harder.
This is not a reason to dismiss any particular brand. It is a reason to ask the question clearly and expect a clear answer.
Ozonators and UV systems: what they do and what they do not do
Many spec sheets list an ozonator or UV system as a headline feature. Both are genuinely useful. Neither eliminates the need for chemicals.
Ozonators generate ozone (O3), which is injected into the water and kills bacteria on contact. Ozone breaks down quickly and does not stay active in the water, which means it handles bacteria near the injector but cannot sanitise the entire body of water on its own. It reduces the chemical load meaningfully. It does not replace chlorine or bromine.
UV systems pass water through an ultraviolet light chamber, which kills micro-organisms by disrupting their DNA. Again, effective at the point of treatment. Effective at reducing the overall bacterial load. Not a complete replacement for a residual sanitiser.
VitaSpa’s CleanZone system combines both ozone and UV in a single unit. That combination is more effective than either alone, and it does reduce the amount of chlorine or bromine you need to maintain safe water. Running costs on chemicals are lower. But the system still requires a residual sanitiser. If a salesperson tells you that an ozonator or UV system means you do not need chemicals, that is not accurate.
The honest framing: these systems reduce chemical use, keep water cleaner between doses, and mean you spend less time testing and dosing. They are a genuine benefit. They are not magic.
Warranty: reading the small print
A “10-year warranty” sounds reassuring. Read what it actually covers.
A hot tub has several distinct components, and most manufacturers offer different warranty periods for each:
- Frame. Often the longest coverage, because the frame rarely fails and the promise costs the manufacturer little.
- Shell. Usually several years on structure, less on surface.
- Plumbing. Typically one to three years. Plumbing is where failures happen. Read this closely.
- Electrical components and pumps. Usually one to two years. Pumps are the most commonly replaced item on any hot tub.
- Cabinet. Usually one to two years on materials and workmanship.
- Heater. Often one year.
A manufacturer advertising “10-year warranty” may be referring only to the structural frame. The electrical components and plumbing, which are the parts that actually fail in normal use, may have one-year cover.
Ask the dealer to show you the warranty document and walk through what each period covers. The breakdown tells you more about the manufacturer’s confidence in their own product than the headline number does.
Also ask: is the warranty serviced by the dealer, or do you have to contact the manufacturer directly? A dealer who services their own warranties is a different proposition to one who points you to a call centre abroad when something fails at year three.
A checklist you can take to any showroom
The questions below will not take long to ask. A confident, well-trained dealer should be able to answer all of them without hesitation. A dealer who cannot, or who deflects rather than answers, is telling you something important.
- How many of those jets are directional and adjustable, and which seats are they in?
- Can you describe the insulation system, step by step, from the water to the outside air?
- What is the frame made of, and how is it treated?
- What control system does this tub use, and who manufactures it?
- Is the shell acrylic? If so, which supplier?
- Where is this tub manufactured?
- Does the ozonator or UV system reduce chemical use, and by roughly how much?
- Can you show me the warranty document and walk through what each period covers?
- If something goes wrong in year four, who do I call and what happens next?
One honest closer
Take this list to every showroom you visit. That includes ours.
If we cannot answer any of these questions clearly, you should hold us to the same standard as anyone else. We would rather you walk in having done your homework than buy on the strength of a confident-sounding pitch. The tub will be in your garden for fifteen years. The questions are worth asking.
If you want to talk through any of this before visiting, you can call the showroom or drop us a message. No obligation, no follow-up unless you want one.