Swim Spas

How does a swim spa work?

how does a swim spa work explained

A swim spa or exercise pool is a little like a very large hot tub, by proving resistance it allows you to swim on the spot. Think of a swim spa as being the swimming equivalent to a treadmill. Instead of the floor moving beneath your feet, the water flows past you and you must swim in order to stay stationary. They offer more versatility than a traditional pool, as well as saving both space and money. So now you are up to speed with what they are, let’s look at how does a swim spa work.

A basic look at how a swim spa works.

A swim spa works by creating a current of water that flows from one end of the pool to the other. This provides the swimmer a level of resistance to work against. There are several popular methods of providng this current. The most common of which are water pumps forcing water through jets that point the length of the spa. There will also need to be some form of control over the speed of the current so that it can accommodate differing abilities.

An in-depth look at how a exercise spa produces a current

Pump driven current

The majority of swim spas on the market will have a water pump driven swim current. These pumps are very similar or the same as what you would find in a hot tub. They are powerful, shift large volumes of water and are easily controllable.

The water is first drawn through filters that are built into the spa itself, where any foreign objects are removed. Then passing down internal pipework it will reach a centrifugal water pump, where it is forced back out at over 600 litres per minute!

This water will now pass down further pipework where it will go through a diverter valve. A diverters job is to control where the flow of water goes, fully open it will send 100% to the swim jets for maximum performance. Half way open it would send the other 50% to the seating area in the spa, reducing the speed at the swimming end. Think of a diverted as being like a volume dial to your swimming effort.

The last leg of the journey is to the actual jets themselves at the far end of the spa. At this point, the water may also be mixed with air to increase the perceived power of the flow. Whilst this does make the flow feel and look more energetic, it can also increase turbulence which may not be desired by some swimmers. We have an article here about the differences between air injected and airless jets

A very popular pump driven swim spa is the Challenger 15D, its three pumps and airless jets offer a great swim for beginners and experts alike.

How does a swim spa work, explained graphic
The main components of a pump driven swim spa

Propeller driven current

Propeller driven units are far less common as they are typically more complex to produce and therefore carry a premium price tag. However they are able to offer the fastest and most controllable water currents. In addition to this, they are regarded as having the smoothest water flow of all propulsion systems.

These units do not normally draw the water through filters, pipework and diverters. Instead the water is drawn directly into the propulsion unit through gratings before being forced back out again by the propeller.

Since these units would normally have a variable speed motor controlling the propeller, a high degree of adjustability is possible. Its not uncommon for there to be 100 steps from zero to full power, allowing the swimmer to achieve the exact resistance level they wish for. A perfect example of a spa that has this level of power and control is the Michael Phelps Signature Deep.

Filtration is taken care of by a separate water pump, so you will still enjoy clear water in a spa of this design, it’s just achieved through different means.

How a swim spa works with a propeller
Propeller swim spas offer tremendous power and control


We hope from this post you have learnt how a swim spa works and perhaps have an idea of which type may be best for you. For many people a pump driven swim spa is the perfect combination of performance and price, giving them all they will ever need. However if you are a particularly strong swimmer or wish to have the ultimate training tool to become one, then a propeller driven unit could be your ideal choice.

If you are looking to take the next steps, our recommendation would always be to come and see them in our showroom. Its only by seeing and experiencing a swim spa that you can get a feel for what they can offer, with demo units available we can even book you a test swim!