Can I Use a Variable Speed Pump in a Hot Tub?

Last updated: September 2026

This question doesn’t come up as often as some, but when it does, it’s usually from someone who’s done their homework. Variable speed pumps are everywhere in the pool world now, and they’re brilliant at saving energy. So why not use one in a hot tub?

There’s a lot of confusion around this, so let me start with a clear answer: don’t use a variable speed pump as the jet pump in your hot tub. But there’s a place where one can make a lot of sense. Read on and I’ll explain both.

What is a variable speed pump?

A variable speed pool pump has a motor, usually driven by built-in electronics with a digital control panel, that can run at any speed across a wide range rather than one or two fixed speeds. You set it to the speed the job needs: slow for everyday filtration, faster for vacuuming, heating or running a water feature.

The reason they’re so popular is energy. The power a pump uses drops dramatically as it slows down. ENERGY STAR explains that “reducing pump speed by one-half allows the pump to use just one-eighth as much energy”. Because a pool pump runs for many hours a day, running it slowly for longer saves a lot of money. They’re quieter at low speed too.

In the USA, they’re now effectively the norm for pools. Under the Department of Energy rules that came in from July 2021, new inground pool filter pumps over 1.0 total horsepower generally need to be variable speed to meet the efficiency standard. Spa filter and circulation pumps are excluded, which tells you something about how different the two jobs are.

Variable speed vs two-speed hot tub pumps

A variable speed pump and a dual-speed hot tub pump are not the same thing, even though both run at more than one speed.

	Variable speed pool pump	Two-speed hot tub pump
Speeds	Any speed in its range	Two fixed speeds: low and high
Controlled by	Its own control panel, a timer or pool automation	The spa pack and topside buttons
Designed for	Volume at low pressure, for long filtration runs	Low for filtration, high for jet pressure
Usually	Self-priming, with a strainer basket	Centrifugal, fitted below the water line
Cost	Much higher	Lower

In a hot tub, a two-speed pump is ideal because it does both jobs with one pump: low speed for filtration and heating, high speed for the jets, all switched from the topside. There’s more on pump layouts in How many pumps do you need?

Why a variable speed pump is wrong for the jets

1. Jets need flow, and slow means no flow

Jets need a lot of water. Gunite jets are rated at around 10 GPM each (Waterway’s jet instructions give 10 GPM), so a 16-jet tub needs about 160 GPM. A variable speed pump’s savings come from running slowly, but as the speed drops, so does the flow and pressure. Slow flow is exactly what jets don’t want. Run it fast enough to drive the jets properly and you’re back at full power, with most of the saving gone.

2. Pool pumps aren’t built for jet pressure

Even at full speed, pool pumps are designed to move a lot of water at low pressure. For example, Pentair’s SuperFlo VS manual shows a maximum of around 130 GPM, and that’s with almost nothing to push against. By the time the water has gone through the pipes, fittings and jets, it’s far less. I’ve gone into why pool pumps disappoint on jets in Swimming pool pumps: the shocking truth.

3. The spa pack can’t control it

A spa pack is essentially a set of relays. It switches a pump on or off, or, with a two-speed pump, selects low or high. It can’t “set” a speed.

Connect a variable speed pump to a spa pack’s pump output and it’ll run at whatever speed its own controller is set to, whenever the pack switches it on. Some variable speed pumps do have low-voltage inputs to select preset speeds. The SuperFlo VS, for example, has speed inputs that accept 5–30V signals. But a spa pack’s pump output is mains voltage, so you’d need an extra relay in between, and even then you only get one or two fixed speeds. You’d have paid a lot more for a pump that behaves like a two-speed one, only with less jet pressure. My hot tub wiring guide explains how the pack switches the pumps.

4. Hot tub jet pumps don’t run all day

The big savings come from pumps that run for many hours a day. A hot tub’s jet pump runs on high when you’re in it, and for filter cycles on low. There’s far less running time to save money on. If you want to cut running costs, the heating is where the money goes. See Hot tub energy efficiency and the best way to heat a DIY hot tub.

Where a variable speed pump does make sense

Variable speed pumps are brilliant for filtration. So if your build has a separate filtration and heating loop, with its own pump, filter and heater, and not the spa pack’s circulation, a variable speed pump is a good choice for that loop. Typical examples:

• A hot tub with a sand filter. A sand filter needs its own pump, as I explain in Can I use a sand filter on my DIY hot tub?
• A hot tub with an air source heat pump on its own loop. See How to add a circulation pump to a hot tub and the guide to air source heat pumps for hot tubs.
• Spools, plunge pools and pool combos, where the filtration pump runs for long hours. See Why pool and hot tub plumbing should stay separate.

The jets still get their own proper jet pump. If you’re choosing the filtration pump, my pool pump upgrade tips will help.

On a typical DIY hot tub, where a two-speed pump or a small circulation pump runs the filtration through a cartridge filter, a variable speed pump is overkill. A spa circulation pump is small, cheap and draws very little power.

Common mistakes

• Using a pool pump, variable speed or not, as the jet pump, then wondering why the jets are weak.
• Wiring a variable speed pump to a spa pack and expecting the topside to control its speed.
• Putting a self-priming pool pump on the jets because the control room is above the water line. See self-priming hot tub pump options instead.
• Sizing a pump by horsepower alone. See How to correctly size a hot tub pump.

Want it drawn up for you?

Choosing pumps is really about the whole plumbing design: the jets, pipe sizes, filter and heater all have to work together. My DIY hot tub plans include the plumbing layout and pump choices for each size. For a custom build or a pool combo, the Tub & Pool Designer Pro plumbing design service sizes the pumps and pipework for you.

Hot tub jet pumps and circulation pumps are available from parts4tubs.co.uk in the UK and parts4tubs.com in the USA. For the bigger picture on pumps, see The ultimate guide to all things hot tub pump.

FAQs

Can I use a variable speed pump in a hot tub?

Not as the jet pump. It can’t give the jets enough flow and pressure efficiently, and a spa pack can’t control its speed. It does work well on a separate filtration and heating loop.

Can a spa pack control a variable speed pump?

Only as on/off, or on one or two preset speeds through an extra relay. A spa pack can’t set a variable speed.

Is a two-speed hot tub pump the same as a variable speed pump?

No. A two-speed pump has fixed low and high speeds switched by the spa pack. A variable speed pump can run at any speed in its range and has its own controller.

Will a variable speed pump save money on a hot tub?

Not much on the jets, because they only run when you’re in the tub and need high speed. The savings come on long filtration runs, such as a pool or a separate hot tub filtration loop.

Can I use my pool’s variable speed pump for hot tub jets?

Not if you want proper hot tub jets. Give the jets their own jet pump and keep the pool pump for filtration and heating.

Weighing up pumps for your build? Ask in the comments below. I read them all.

Cheers,
Andi

You can also find me on my socials;

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

Thanks - Andi

 

Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi