Seats, jets, and the heater that has to hold against a winter night
An outdoor spa is a heated, filtered, jetted tub, and the versions on this shelf run from a drop-stitch inflatable wall to a rigid insulated cabinet. The stated capacity in people is the least reliable figure on the listing — a "6 person" spa of 185 × 185 cm gives each person a width narrower than an airline seat — so the number to read is the internal dimension and the seat count moulded or marked into it. The figure that decides the running cost is the heater power, typically 1,5 to 2,2 kW, together with the stated heat-up rate in degrees per hour: a 1,5 kW heater raising 900 litres manages roughly 1,5 °C an hour, which means a spa filled from a cold tap is a next-day proposition. Insulation is what decides whether that heat stays: an insulated cover, a base mat and, on the better inflatables, a second internal wall layer. Then the jets, and here the words matter: bubble jets are air blown through the floor and cool the water while they run; hydro jets are pumped water and are what most buyers picture. A spa listing that says only "jets" is usually describing the first. Filtration is a cartridge, changed far more often than a pool's because the volume per bather is a fraction of a pool's. And winter use, which several makers now state explicitly with a minimum ambient temperature. We compare footprint and seats, heater power and heat-up rate, insulation, jet type and count, filtration and stated winter rating.
Replacement tub only — delivered without pump or control panel
Not a working spa. Mendler states in its own feature list that this is delivered without a pump or control panel — it is a replacement tub for an existing unit, and the title does not say so.
Best for: Replacing the tub of a spa whose pump unit still works
185 × 185 cm, 910 l, 2 400 W total, 130 jets, 20–40 °C
The most completely specified spa here: 1 800 W of heating plus 600 W of blower, 910 litres in a 185 cm square, 130 air jets, and a temperature range published from 20 to 40 °C.
Best for: A six-person spa where the electrical draw needs to be known before it is plugged in
4–8 people, UVC-PLUS, Rhino-Tech, MDC pump 1 800 l/h
An MSpa-built spa with ultraviolet disinfection stated to remove 95 % of bacteria, a Rhino-Tech shell claimed UV- and frost-resistant, and an MDC pump publishing a flow of 1 800 l/h.
Best for: A spa chosen on water treatment rather than on bubbles
Ø 200 cm, 6 seats, 140 AirJets, 1–2 °C/h to 42 °C
The only spa on this shelf that publishes a heat-up rate — one to two degrees an hour to a maximum of 42 °C — with 140 air jets, three-layer PVC, two cartridges and a chlorine dispenser in the box.
Best for: A first spa where knowing how long it takes to warm up decides whether it gets used
Ø 216 × 71 cm, 6 people, bubble massage
The largest footprint in this family at 216 cm across, from a listing that publishes one line: the size, the seat count and the fact that it bubbles.
Best for: Somebody who already knows the PureSpa range and is buying on size
130 jets, 2 400 W, frost protection below 5 °C, carry bag
A 2 400 W spa with 130 jets, a reinforced base and a frost protection that switches the heating on when the temperature falls below five degrees — published as a threshold rather than as a claim.
Best for: A spa that will be packed away between seasons and carried
Ø 180 × 66 cm, 669 l, FreezeShield from 6 °C, size VI cartridges
The spa that publishes its winter behaviour as two temperatures: FreezeShield starts the heater at 6 °C and stops it at 10 °C. Two size VI cartridges and a chemical dispenser are supplied.
Best for: A four-person spa expected to stay outdoors through a winter
4 people, foam-insulated, 70 AquaJets, WiFi, 104 °F
A foam-insulated spa rather than a purely inflatable one, with 70 water jets, WiFi control, and a stated 50 % greater thermal efficiency from its insulation.
Best for: A spa used through cooler months, where holding heat matters more than bubble count
160 × 160 × 65 cm, 6 people, 120 jets, UVC+, app control
The dearest spa here: a six-layer Rhino-Tech shell in a wood finish, 120 air jets with neck and seat padding, UVC+ water treatment and control from the MSpa Link app.
Best for: A spa chosen on finish and on app control, where the shell construction is the argument
Only the specifications at least four models out of five state. A column that is more empty than full compares nothing.
| Model | Price | Amazon reference | Filtration | Footprint | Heat-up rate |
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Specifications: manufacturer sheets and Amazon product pages. Prices and availability: Keepa. No product on this site has been physically tested.
Most recent revision in this category: September 21, 2026.
