The St Lawrence 20

Two independent water volumes inside one shell. The swim end runs at whatever temperature you want to exercise in — typically 28 °C for laps. The hot tub end runs at soak temperature — typically 38 °C. A sealed internal bulkhead separates them; the water doesn't mix. Each zone has its own Balboa controller, its own 3 kW heater and its own pump bank. One person can swim in the cool zone while another soaks in the hot zone — same shell, same evening.

The alternative — a single-temp swim spa — forces you to pick one temperature for everything. If you want to swim cool, you soak cool. If you want to soak hot, you swim hot. Dual-zone removes that compromise.

The packaged spa is 597 × 231 × 150 cm and weighs 1,730 kg — this is a genuine HGV-only delivery, not something a domestic pallet truck can handle. Free flatbed delivery to mainland UK is included; you arrange a HIAB or crane lift from the back of the lorry onto your base. We do not book the lift for you — a local operator near you will nearly always be cheaper than one we book from Surrey.

Because swim spas are bespoke per customer, we build the delivery plan with you by phone before you order. Call 01293 824 094 with photos or a sketch of your access route — we work through HIAB reach, base readiness, neighbouring trees, overhead cables and electrical supply together before a deposit goes down. That conversation is worth doing before you order, not after.

Typical HIAB/crane costs for a 20 ft swim spa: £400–£900 for a standard lift, more if the reach is long or the garden access is tight. The operator will usually do a site survey or check your property on Google Maps for free. Once on the base, our team fills the spa, walks you through both control pads, and hands over. Electrical connection is separate — see the electrics FAQ.

The St Lawrence 20 is hardwired. There is no 13 A plug-and-play shortcut — five 5 HP pumps and two 3 kW heaters together draw more current than a domestic ring circuit can deliver. Two dedicated supplies are required:

• 50 A supply for the swim-end zone (pumps + one 3 kW heater)
• 32 A supply for the hot-tub-end zone (pumps + one 3 kW heater)

Both run 230 V, both sit on their own RCD in your consumer unit, both terminate at an outside rotary isolator before entering the cabinet. Your electrician runs the armoured cable, fits the isolators, and leaves roughly 5 m of slack outside the spa footprint so our installers can bring the tails into the cabinet on delivery day. None of this kit — RCDs, isolators, armoured cable, glands — is supplied with the spa. It's a straightforward job for any competent spark familiar with swim-spa installs, but please have them lined up and both cable runs done before delivery. Electrical first-fix sits outside our delivery and installation service.

A 6″ (150 mm) reinforced concrete pad, sized to the full footprint of the spa — 600 × 235 cm minimum. This is thicker than the 3–4″ pad a standard hot tub needs, and the reason is straightforward: filled weight is 8,930 kg. A swim spa does not tolerate settlement or unevenness. An equivalent-strength engineered patio (structural slabs on a rigid mortar bed over a reinforced sub-base, rated for the filled weight) also works — talk to us first if you want to go that route.

Specify steel reinforcement (mesh or rebar), a compacted hardcore subbase, and a properly power-floated finish. Slabs alone are not an option at this weight — we see cracked slab bases fail on swim spas every season. If you want to run your base plan past us before pouring, send photos to the team and we'll check it.

Two separate layers, both included as standard:

2 years parts & labour — shell, pumps, heaters, and control systems across both zones. If something fails in normal use, we replace the part and fit it, anywhere in the UK. No annual service required to keep cover active — a condition some brands attach to void your warranty if you miss a year.

10 years against water loss through the shell structure — structural protection for the acrylic body.

You can also extend parts & labour by a further 2 years. Swim Spas sit at the top extended-warranty tier — £1,200 (vs £500 Patio Spas, £850 acrylic hot tubs). The extension is stackable — buy it twice and you get four additional years — and can be purchased any time while still under warranty.

Running cost on a 7,300 L dual-zone swim spa sits above the £2–£2.50/day figure for a standard hot tub, because you're heating more water and potentially running two zones at temperature. Actual cost depends heavily on use pattern — a household that swims three mornings a week and soaks most evenings uses more energy than one that only runs the hot tub side daily and warms the swim end for a weekly session.

Rough guidance for a typical UK household running both zones at their default temperatures year-round: expect monthly costs broadly in the £100–£180 range, weighted toward the upper end in winter. Pairing the spa with a heat pump (Balboa Clim8zone II or similar) typically reduces that meaningfully. Call 01293 824 094 for a model based on your use case and tariff — we run the numbers honestly, not optimistically.

The St Lawrence 20 ships with a 200 ft² antimicrobial filter set installed — roughly twice the surface area of a standard hot tub filter, because there's roughly twice the water to keep clear. The media is antimicrobial-infused to inhibit bacterial growth on the filter itself. Paired with the Mountain Pure™ UV-C lamp and built-in ozone generator, the result is cleaner water with fewer chemicals.

Replacement schedule: every 4–6 months, or sooner if discoloured. Keeping a second set on rotation is the standard owner trick — swap in a clean set on top-up day, rinse the used set overnight.

Households that specifically need simultaneous swim-cool + soak-hot with two different people in at the same time. Typical buyers: couples where one partner trains seriously at 28 °C and the other wants a 38 °C soak waiting for them when they're done, families with teenagers plus older relatives (different temperature preferences, same evening), and rehab-use households where the therapist runs resistance work in the swim end while the patient transitions to the hot end for heat therapy after.

If you don't need simultaneous different temperatures and you want pure swim performance, our flagship is the shorter St Lawrence 16 (500 × 228 × 137 cm · 19 HP · stroke-swim without a tether) — it's the Balboa horsepower ceiling in our range and the model most swim-spa customers choose. If you only want the hot-tub experience (no swim element), the Niagara (228 × 228 × 99 cm · 60 jets · 2 × 5 HP + blower · diverter valves) is our flagship acrylic and costs considerably less. If you want to sit in a St Lawrence 20 before committing, book a showroom visit — it's the right call on an order of this size.

Yes. The whole design target is year-round UK outdoor use: closed-cell foam wrapping the plumbing, an infrared-lined cabinet reflecting radiant heat back into the water, and a hardtop locking cover across both zones. Two 3 kW Balboa heaters (one per zone) keep both zones at setpoint independently. The typical use pattern is: hot tub side running 24/7 at 38 °C; swim side warmed from ambient up to 28 °C in the day or two before a swim session, then held there through the training block.

Everything in the What's in the shell list: the spa itself, both heaters, both control pads, brown two-piece hardtop cover, full LED mood lighting, Bluetooth pop-up speakers, aromatherapy canister, two cascading waterfalls, swim tether pole, installed 200 ft² filter set, Mountain Pure™ UV + ozone sanitation, all manuals, and free flatbed delivery to mainland UK. Optional add-ons: 2 × top-mount cover lifters (one per cover half), chemical starter kit, and the Swim Spa tier extended warranty.

What we do not supply: the HIAB/crane lift (arranged locally — see the delivery FAQ), the electrical first-fix (50 A + 32 A RCDs, isolators, armoured cable, glands — fitted by your electrician before delivery), or the concrete base. These three pieces sit outside our scope and are where most swim-spa delivery friction comes from — plan them early.

Yes — and at this price point it's the right call. Our showroom is at Canada House, Unit 1, Salbrook Road, Redhill, Surrey · RH1 5GL. Ten minutes from Gatwick. Open Monday–Friday 9am–6pm and weekends 10am–4pm. Please call ahead (01293 824 094) for a swim-spa visit so we can have the St Lawrence 20 set up and filled for a proper wet test.