The St Lawrence 16

Longer, yes — but not more powerful. The Balboa control system caps total pump output at 19HP, and we've built the St Lawrence 16 right to that ceiling. Our 13ft and 20ft swim spas both run at 15HP (the 20ft splits that across two independent temperature zones, so the swim end sees less again). The 16ft is the model with the most swim-end horsepower in our range, full stop — 4HP more than either sibling — and it's the one most customers end up buying.

The practical tell is the tether. On smaller / lower-power swim spas, the tether is essential — the current can't hold a proper stroke by itself. On the 16ft the tether is optional: the 19HP current holds breaststroke, butterfly and freestyle untethered for most swimmers. That's what makes it the casual-swimmer favourite — you climb in, swim, and climb out, without strapping into a harness every time.

Usually not. The 19HP current is strong enough for proper stroke swimming — breaststroke, butterfly and freestyle — without relying on the tether. An adjustable tether and swim harness are included as standard, and they're useful for stroke-technique work or for swimmers who want extra stability, but most owners only clip in occasionally.

One detail that matters for breaststroke and butterfly specifically: you can turn the air out of the water flow. That gives you a smooth, powerful riptide instead of a bubbly washing-machine foam — crucial when your face is in and out of the water and you're trying to breathe without inhaling bubbles. Dial the air back in for casual float-and-play and the fun factor returns.

Most customers run the St Lawrence 16 at around 35 °C year-round. That's cold enough to climb into for a morning swim without feeling overheated five minutes in, and warm enough that after a longer session the water reads as a proper warm soak rather than a cool pool. The shell holds setpoint regardless of ambient weather — the Balboa heater, closed-cell foam insulation, and IR-lined cabinet do that work.

A note on thermodynamics vs. a hot tub you may have owned: a swim spa is a deep pool of water, so even when you're wading around at the spa end rather than swimming, you're submerged further and for longer than in a standard hot tub. Heat transfer into your body is higher. The rule of thumb most owners settle on: run a swim spa about 1 °C lower than the setpoint you'd use on a hot tub. If your old hot tub sat at 40 °C, run the XTrainer at 39 °C. If you set a hot tub at 38 °C, the XTrainer sits happy at 37 °C. Push higher and you'll feel lethargic from overheating before the session is done.

The packaged spa is 502 × 230 × 149 cm and weighs 1,460 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 16 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 the control pad, and hands over. Electrical connection is separate — see the electrics FAQ.

The St Lawrence 16 is hardwired. There is no 13 A plug-and-play shortcut — four pumps (19 HP total) and a 3 kW heater together draw more current than a domestic ring circuit can deliver. One dedicated supply is required:

• 50 A supply (pumps + 3 kW heater) — 230 V

The supply sits on its own RCD in your consumer unit and terminates at an outside rotary isolator before entering the cabinet. Your electrician runs the armoured cable, fits the isolator, 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 — RCD, isolator, 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 the cable run 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 7,835 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, heater, and control system. 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 6,475 L shell sits above the £2–£2.50/day figure for a standard hot tub, because you're heating roughly four times the water volume. Actual cost depends heavily on setpoint and use pattern — a household holding 35 °C year-round and swimming three mornings a week runs warmer than one that keeps it at 33 °C and dials up only for sessions.

Rough guidance for a typical UK household holding the shell at the 35 °C sweet-spot setpoint year-round: expect monthly costs broadly in the £80–£140 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 16 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.

Casual-to-serious swimmers who want a real swim — not just a splash — in a single piece of kit that also does top-tier hydromassage. Because the current is strong enough to hold breaststroke, butterfly and freestyle without a tether, this is the swim spa for people who want to climb in, swim, and climb out without strapping into a harness. Typical buyers: swimmers without a nearby pool, people doing low-impact rehab work, households wanting morning laps and evening soaks in the same shell, and anyone who priced the cost + upkeep of a heated outdoor pool against a swim spa and walked toward the swim spa. It's the model most customers choose.

Where the siblings make sense: if you need to swim cool (28 °C) and soak hot (38 °C) on the same evening with different people in at the same time, the dual-zone St Lawrence 20 (sealed bulkhead, two heaters, two controllers) is the specialist model — longer footprint but 15HP total, so the swim is slightly less powerful than the 16ft's 19HP. 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 16 before committing, book a showroom visit — at this price point it's the right call.

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. A 3 kW Balboa heater holds the shell at setpoint regardless of ambient temperature. The typical use pattern is to hold the water at around 35 °C year-round — cool enough to climb straight into for a morning swim without overheating, warm enough after a session to feel like a hot tub for the evening.

Everything in the What's in the shell list: the spa itself, 3 kW Balboa heater, Balboa control pad, 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 RCD, isolator, 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 16 set up and filled for a proper wet test.