Master Spas MP Momentum D

Master Spas builds four kinds of current. The Michael Phelps models push water with a belt-driven propeller set in 100 steps; Challengers use six airless jets fed by three pumps, Trainers four air-injected jets from two pumps, and Therapools a two-speed stream that Master Spas says may not be ideal for stationary swimming. On the Trainers, Challengers and the Therapool SE and D the swim pumps also feed seats or the therapy cove through diverters (on the Therapool 13 and 15 one pump runs only the swim end), and no flow, width or horsepower is published for any current.

Applies to: All 15 current models; the verdict differs by line (MP propeller best, Challenger and Trainer jets acceptable, Therapool a therapy stream).

What this means, and how to check it →masterspascdn.com ↗masterspascdn.com ↗

Master Spas publishes only outside cabinet sizes, 11 to 21 feet long and 51 or 60 inches tall (48 on the Therapool 13), plus 'around 51 inches' of water depth for the MP series. It calls the two 19D MAX models the largest H2X swim areas but prints no open-lane length or width for any model, and the 21-foot dual-zone models give part of their length to a sun deck and a hot tub.

Applies to: All 15 current models.

What this means, and how to check it →masterspascdn.com ↗michaelphelpsswimspa.com ↗

Master Spas lists a coated wood frame with fiberglass-reinforced billets at the top flange, full-foam insulation and, on the Michael Phelps models, a high-density polymer base. It publishes no shell laminate, frame gauge or design for any swim spa, and its structure warranty (10 years, 7 on Therapool) covers water loss, with removal and replacement of a failed unit at the owner's cost.

Applies to: All current H2X and MP swim spas; brand-level statements, no model-specific frame spec.

What this means, and how to check it →h2xswimspa.com ↗michaelphelpsswimspa.com ↗

The 2026 manuals ask for a concrete pad at least 4 inches thick with crossed rebar on a firm, level surface, warn that a crane may be needed, and list full weights up to 24,775 pounds, advising 15% extra when planning delivery. Most H2X models need one 50-amp GFCI circuit, the 21-foot H2X models two, the MP Signature Pro one 60-amp, and the MP Momentum D three circuits totaling 130 amps; Challengers also need specific GFCI breaker brands.

Applies to: All 15 current models.

What this means, and how to check it →masterspascdn.com ↗masterspascdn.com ↗

Master Spas insulates every H2X and MP swim spa with full foam. Nine exercise-spa listings in California's database carry current model numbers, at 241 to 483 standby watts, or 47% to 82% of each size's limit. The two for the 15D models list about 1,900 gallons against the 1,595 Master Spas now publishes, so our model pages use only the other seven. The Momentum D's hot tub side uses 191 of its 197 allowed watts, and we found no matching listing for the 19- and 21-foot H2X models.

Applies to: All 15 current models for insulation; California listings found for 10 of 15, seven used on model pages.

What this means, and how to check it →h2xswimspa.com ↗michaelphelpsswimspa.com ↗

Each splits the cabinet into two bodies of water with independent temperature controls and separate control systems. The 21-foot H2X models put 370 gallons on the hot side and need a second 50-amp circuit; the Momentum D uses a clear acrylic divider, a 275-gallon hot side and three circuits totaling 130 amps. Master Spas publishes no figure for heat crossing the divider.

Applies to: Trainer 21, Trainer 21D, Challenger 21D, MP Momentum D; the other 11 models are single-zone.

What this means, and how to check it →h2xswimspa.com ↗michaelphelpsswimspa.com ↗

The manuals name the main equipment panel for each model, say every side must stay reachable, and fit slice valves and unions so pumps and the heater can be serviced without draining. The warranty doesn't pay for access and lets dealers charge travel and access fees; full foam makes plumbing leaks slower to reach, and the MP propeller's critical parts must be identical factory components.

Applies to: All 15 current models; propulsion notes apply to the two MP models.

What this means, and how to check it →masterspascdn.com ↗masterspascdn.com ↗

The 2026 cards pay parts and labor on structure, surface, equipment and plumbing repairs, while jets and skirting are parts only. Structure means water loss, and if a spa is replaced the owner pays removal, reinstallation, access and any deck or fence damage; covers and freeze damage are excluded, the MP propeller has only 2 years, and the Therapool product pages still show the longer Trainer terms.

Applies to: All 15 current models; Therapool terms shorter; MP propulsion line only on the two MP models.

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Every model ships with the Deluxe Quad-Fold Cover, which Master Spas says meets ASTM F1346 for lockable safety covers; the MP site lists 5- to 3-inch tapered foam. Manual and hydraulic lifts are extra, the Axis roll-up cover is an option with a 3-year parts-only warranty, and the 21-foot H2X models can take a hybrid Axis-and-foam cover.

Applies to: All 15 current models; hybrid cover only on Trainer 21, Trainer 21D and Challenger 21D.

What this means, and how to check it →h2xswimspa.com ↗michaelphelpsswimspa.com ↗

Claims go in writing to the selling dealer within 10 days. If the dealer won't act, the owner contacts Master Spas. The dealer or an approved independent service center inspects the spa, and dealers may charge for travel. Controls are mainstream Gecko and TP500 systems, while the MP propeller's critical parts come only from the factory.

Applies to: All 15 current models.

What this means, and how to check it →h2xswimspa.com ↗michaelphelpsswimspa.com ↗