Saltwater Systems for Hot Tubs: Yes or No?

Saltwater systems have flooded the marketplace as an alternative or natural way to sanitize your hot tub. However, is it really better? Let’s take a closer look at salt systems so you can make the best decision for your hot tub lifestyle.


Salt water pool systems were developed around 1980. Originating in New Zealand, the use of electrolysis to convert salt (sodium chloride or sodium bromide) to chlorine or bromine requires electrostatically charged plates or electrodes to convert the sodium to a sanitizer. Put differently, a salt generating system is creating a chemical to sanitize the water. Salt generators for the swimming pool environment are a solution for homeowners who struggle with managing granular chlorine dosing and other chemical additives. While salt generation systems may work for pools there are a few reasons sanitizing generators, either chlorine or bromine, may not be as good a fit for hot tubs.

Differences Matter

Factor in the following differences for a hot tub from a large, cool body of water such as a backyard pool:

  • • Hot tubs are much smaller than a pool, typically 1500 litres.

  • • Hot tubs have very warm water, up to 104⁰F.

  • • A hot tub is covered, it does not allow chemicals to vent, no UV from sunlight.

  • • A hot tub has metal components such as heaters, heater elements and jet faces which will corrode.

  • • A hot tub has more people and less water; which means faster consumption of sanitizer.

  • • A hot tub cannot tolerate calcium build-up which can be a by-product of sodium.

All of these differences matter. A smaller amount of water does require less amounts of any sanitizer. So pool and hot tub water maintenance is not the same challenge. Most hot tubs today are equipped with ozone generators, which can mean even less chlorine or bromine usage to properly sanitize. When you add a mineral salt to soften water, you have a perfect combination creating soft, heated, sanitized water. However, if instead, you use a salt generator system in this higher temperature environment and add bathers, it is quite possible these types of generators may not produce enough chemicals to sanitize properly. Some salt system manufacturers even admit you may have to add additional sanitizer to maintain the water properly.

At the same time, should the generator continue to run and sanitize without bathers (who ‘consume’ sanitizer) for a period of time, it may over-produce sanitizer. Over chlorination may lead to chemical gasses trapped under the cover. This may lead to damage and breakdown of the Spa cover, pillows, controls and filter covers. But that’s just the start, the internals of the Spa like the pumps, seals, heater element and jets are all at risk. Very close attention must be paid to balancing water with salt generators.

Warranty or Chemical Abuse?

Often times corroded heaters or elements are not covered under warranty. The damage is attributed to “chemical abuse” due to over chlorination and calcium build-up. This can result in costly repair bills. When sodium bromide (generator salt) is added to the water, it is not immediately converted or electrolyzed to chlorine, it resides in the water. While many salt generator manufacturers claim the amount of salt is at a minimal level, about 1500 parts per million of salt is required for these systems to work, which can be triple the amount of salt in tap water.

Maintenance? What Maintenance?

For something that is supposed to make sanitizing a hot tub easy, you cannot forget about maintaining this “timesaver”. Key factors to keeping the salt system electrostatically charged plates free of debris require a soak in mild acid; the plates or electrodes are not self-cleaning. Maintenance schedules suggest you clean the electrodes or plates in a mild acid solution, every 90 days. Certainly, having to remove the electrodes from an electrical component in your hot tub and soak them for a specified time until the calcium build up is dissolved cannot be considered a “no maintenance” system.

Something else to realize is that where water goes, there goes salt. When you are done soaking and relaxing in your tub, do you really want to get out and hose down your patio, deck or surrounding backyard? When water is splashed out over the edge of your hot tub, on your deck, in your plants, on the surrounding landscape, you have to dilute the salt solution to prevent damage. Some major manufacturers say on their website if you don’t you could experience a stained deck and damaged plants. No one wants to wash down their deck after using the spa every time; isn’t the whole idea of a hot tub supposed to be relaxing?

Tried and True

With over two decades of experience in hot tubs and hot water maintenance, we remain convinced that the best bet for a properly sanitized hot tub is what has stood the test of time; smaller controlled doses of bromine or chlorine and mineral salts to soften the water. That should be all you need for safely sanitized water and care for your hot tub’s components over time. Technology is great, when it works as advertised. We continually research and test the options out there to see if we can recommend them. But as we have shown, claims that salt systems are “natural”, “chemical-free” and “maintenance free”, while sounding great are not exactly accurate. Nevertheless, all reusable water must be sanitized to be safe. Salt generator system technology produces chemicals, requires maintenance, can have unexpected impact on components and may reduce the enjoyment of ownership and use of your hot tub.

Many high-end hot tubs are available with self-dispensing water treatment systems, designed specifically to slow dose a hot tub to the right level. For an example, Zorra has partnered with Aqua Finesse one of the leading manufacturers of natural minerals to help soften and sanitize water. Couple the minerals with Natural Chemistry chemicals and spa care products and you’ll have easy, clean, safe water in no time at all. Enjoy your hot tub, sit back, relax and soothe away the troubles of the day, confident in the pristine water around you. For more information on water treatment systems you can live with contact