Saltwater hot tubs

A saltwater hot tub is a regular hot tub with a salt system: you dissolve a measured amount of salt in the water, and an electrolytic cell turns some of it into chlorine as water flows through. The chlorine sanitizes the water and breaks back down into salt, so the cycle repeats and you add far less sanitizer by hand.

How a salt system works

The cell sits in the tub's plumbing. When a low current passes through it, dissolved salt (sodium chloride) is converted into chlorine. That chlorine does the same job as chlorine you'd add yourself: it keeps bacteria in check and breaks down oils. Once used, it returns to salt, which is why the salt level stays fairly steady between water changes.

The salt level is low. Systems are set to a target of a few thousand parts per million, compared with roughly 35,000 ppm in sea water, so it's well under a tenth as salty as the ocean. Most people can't taste it. Every system has its own target, so follow the one in the manual.

Most systems let you set the output, and some adjust it automatically. You still check the sanitizer level with test strips or a test kit and raise or lower the output to match how much the tub is used.

What a salt system doesn't do

Salt takes care of most of the sanitizing. It doesn't take care of the rest of the water chemistry:

• pH still needs testing and adjusting. Salt systems tend to push pH up, so many owners add pH decreaser regularly.
• Total alkalinity needs to stay in range to keep pH steady.
• Calcium hardness still matters, which is especially relevant here (see below).
• Shock is still useful after heavy use, and some systems have a boost setting for it.

Our water care guide covers the target ranges and a simple testing routine.

Looking after the cell

Over time, scale builds up on the cell's plates and cuts its output. Depending on the system and your water, you'll clean or inspect it every few months, and the cell itself wears out and needs replacing eventually. Ask about the cost and availability of replacement cells for any system you're considering, because that's part of the running cost.

Built-in or added later

Some hot tubs come with a salt system designed in. Others can have one added. Before adding an aftermarket system to a tub, check the tub maker's warranty: some limit or exclude coverage for damage linked to salt, and some only approve particular systems. A system designed for the tub is the simplest route.

Pros and cons

How much does a saltwater hot tub cost?

It depends mostly on the tub, not the salt. A salt system adds to the price compared with the same tub using chlorine or bromine, and the extra depends on whether it's built in or added. Over the years, you'll buy less sanitizer, but you'll pay for salt, test supplies, pH adjusters and eventually a new cell. Ask us to compare the same tub both ways.

Fraser Valley water and salt systems

Much of the valley has very soft tap water. Langley (apart from Aldergrove), Maple Ridge, Abbotsford and Mission all start with very little calcium, so you'll usually need to add calcium hardness increaser after each fill to protect the heater, the cell and other equipment. Aldergrove's water is much harder, so scale on the cell is the thing to watch there, and Chilliwack sits in between. We stock what you need on our chemicals and supplies page, and you can bring in a water sample for testing.