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The swim current
Of the 186 swim spas we track, 160 make the current with jets, 11 with a propeller and 7 with a paddlewheel, according to the makers' spec sheets.
The current is what you're buying. A wide, smooth, adjustable current lets you swim properly; a narrow, bubbly one pushes you around.
What it is
A swim spa keeps you in place by pushing water at you, and there are three ways to push it. Jets fire water through a few nozzles, often with air mixed in. A propeller, like a boat's, turns behind a grate and moves a wide column of water. A paddlewheel does the same job with a wheel; SwimEx builds its pools around one. What you feel isn't the horsepower on the spec sheet. It's the shape of the water: how wide the current is, how deep it reaches, how steady it stays, and whether it's full of bubbles.
Why it matters
A current narrower than your shoulders hits your head and chest and leaves your hands pulling on still water. Every stroke nudges you to one side, so you spend the swim correcting instead of swimming.
Air makes it worse. Bubbles feel strong on your palm but give you less to pull against, and they get in your face. Water that hits the back wall bounces back as chop, which is why makers shape the shell to calm it: Jacuzzi builds hips into its shell, and Hydropool's Executive models add a current collector at the far end.
Speed control decides who can share it. A two-speed current suits one swimmer; Endless Pools' E500 has 31 pace settings and Hydropool's Aquatic models have ten. None of this shows on paper. Flow figures are each maker's own claim with no common test: PDC quotes nearly 5,000 gallons a minute for its propellers and 690 for its Summit jets. A weak or messy current is the one thing you can't fix after delivery, so check it on a running display before you order.
How makers do it
Propeller behind a flow grate
The good wayA large propeller, often hydraulically driven, pushes a wide column through a grate that straightens it. Endless Pools' E-Series and PDC's TruSwim work this way.
Paddlewheel channel
The good wayA wheel turns in a channel and moves a deep, even sheet of water toward the swimmer. SwimEx builds its residential pools this way.
Airless multi-jet current
AcceptableSeveral large jets with no air mixed in. Master Spas' Challenger uses six; Endless Pools' SwimCross uses four.
Air-injected jets
AcceptableJets draw air into the stream, which feels stronger on the hand. Master Spas describes its H2X Trainer current as air-injected.
Single fitness jet or two-speed stream
AvoidA spa built as much for soaking as swimming. PDC sells Splash as a hot tub and fitness hybrid with one fitness jet.
In the showroom
Check this
- Ask the dealer to run a display at the speeds you'd really use.
- Hold your hand across the current at arm's length. It should feel wide and even.
- Run it from lowest to highest and count the steps. A current with only two speeds limits who can use it.
- Read the spec sheet: propeller, airless jets, or air-injected jets?
Ask this
- Is this current made by a propeller or by jets, and is air mixed into it?
- Do the swim pumps only run the current, or do they also feed the seats?
- Can I see this exact model running before I order?
How each brand does it
All 17 brands publish enough to tell.
Every brand, A to Z (17)
- PartlyAmerican Whirlpool
Jets, not a propeller: 2-3 MAAX Force jets on the M models and DM8, 2-4 'Turbo', 'Power' or unnamed swim jets on the R models.
- PartlyArctic Spas
Jet currents only: six stacked Monsoon jets or the aimable Niagara jet; the Athabascan has no current. No flow, speed or air figures.
- PartlyArtesian Spas
A jet current, usually four 6-inch jets on two 3 HP pumps, with variable speed as an upgrade; on four of the five single-zone models the current itself is an option.
- PartlyBullfrog Spas
Two swim jets and five speeds; Bullfrog publishes no current strength, width or pump size.
- PartlyCal Spas
Jets, not a propeller: two river jets on the 13- and 14-foot models, five on the 16- to 18-foot ones; variable speed costs extra.
- PartlyCoast Spas
Jets, not a propeller: two or three lit, aimable River Jets, each on its own pump. Only the Sport Pro models get variable speed; the 1300 Plunge has no current at all.
- PartlyDynasty Spas
Two or three air-adjustable 'River Jets', each on its own pump, except on the 13' Party, whose two jets share a pump with the seats.
- PartlyEndless Pools
Only the E-Series swims on Hydrodrive, a hydraulic propeller; the X and R Series use airless jets, the R's from one two-speed pump.
- PartlyHydropool
Jets, not a propeller: Trainer models get two patented V-Twin jets on two 5 HP pumps with 10 levels; AquaSport jets are hand-adjusted and the AquaPlay only switches on and off.
- PartlyJacuzzi
Two swim jets on every model except the J-13, whose count isn't published; 4 to 10 hp of swim power, plus buoyancy jets on the bigger ones. Jacuzzi publishes no flow, width or independent test.
- PartlyLPICatalina Swim Spas, Dr. Wellness
Two or three 'river jets' (four on the Tri-Therapy), on most models fed by the seat pumps; LPI gives no flow or speed figures.
- PartlyMarquis
Jets on all four, no propeller. The V174K is Marquis' strongest; the V150s are pitched at recreational swimmers.
- PartlyMaster Spas
Depends on the line: a propeller on the two MP models, airless jets on Challenger, air-injected jets on Trainer, a two-speed stream on Therapool.
- PartlyPDC Spas
TruSwim pushes a 29-inch-wide current with two propellers; Summit and Synergy use 3 or 2 swim jets; Splash has one fitness jet.
- PartlySundance Spas
Jets on every model. The Surf 17 gets two 5 HP swim pumps and 10 speeds; the Stream and Splash push two jets with 4 HP.
- YesSwimEx
A paddlewheel current on seven of eight models and a propeller on the Triton, both turned directly by an electric gearmotor with 100 speed settings. The paddlewheel is the approach our checklist rates best; the catch is that SwimEx gives no current width, top speed or tested flow.
- PartlyWellis
Pump-driven currents only: W-Flow (six speeds, 50–60 cm wide) or two or three Riverjet jets.
Read nextBest swim spas for lap swimmingBest swim spasSwim spa sizesSwim spa costSwim spa electrical requirements
Where it gets complicated
Propeller makers call their current the smoothest; Master Spas says its airless jets are turbulence-free too, and we found no independent test comparing them. Flow figures don't settle it because each maker measures its own way. Serviceability cuts the other way: a hydraulic propeller drive has scheduled overhauls, while jet pumps are ordinary parts any technician can replace.