Salt Water Pools: Understanding When and Why They’re Used | Foss Swim School

By Jon Foss

It’s a question we hear from customers on a regular basis: Does FOSS use salt water generators as part of the water purification in its pools? The short answer is that we DO have salt water generators at some of our locations, but the answer our customers are ACTUALLY looking for is more complicated than that. You see, salt water purification is a complex process that is not appropriate in every situation, and contrary to popular belief, even a salt-only system is not “chlorine free” – I’ll explain more about that in a moment.

First, a little context: Salt pools have become increasingly popular in recent years, and with good reason: To many swimmers, salt water feels better on the skin and may feel less “prickly” when they towel off, and for small, personal pools with a light swimmer load, salt water pools can eliminate the need to handle concentrated chlorine.

Long ago we at Foss Swim School set the goal of being expert in every aspect of running pools and teaching swimming, all part of our promise to offer the best experience to students and their families. We have researched and utilized the best in technology throughout our 25 years. With that in mind, here are some things to consider about salt water purification.

Salt water purification is a chemical reaction and is NOT chlorine free

In overly simplistic terms, here is how salt-water purification works:

  • Salt is added to water at a rate of 3,500 parts per million (PPM), 10% of the level of salt in ocean water
  • Electrical current is run through the water in a generator in-line with the pool pumping system
  • In an electro-chemical reaction, some of the salt molecules are changed to create chlorine
  • The chlorine produced is the sanitizer that operates in a salt water pool – salt itself is neither a sanitizer nor an oxidizer, but the remaining salt in the water can affect the “feel” of the water.

In fact, this electrical process is how chlorine is produced for pools – in a salt water pool, the process simply happens at the pool location instead of happening offsite, and with some added dissolved solids left in the water.

What does this mean? Salt water pools are neither chemical free or chlorine free – and they can’t be! For a pool to be safe and bacteria free, chlorine must be present, whether that chlorine comes from a salt reaction or the direct addition of chlorine.

How salt systems are used in some FOSS pools – and why we don’t emphasize it

What we promise at Foss Swim School is the best, cleanest, safest pool experience possible – no matter how we get it. In some locations this includes a salt-water system (backed up by a chlorine system – while salt water can work alone in small pools with light swimmer loads, there is too much variation in a large, heavily used pool to rely on salt alone.)

So even though salt is part of the solution at pools where the water source, pool size and other factors make sense, we want people to know that their pool is clean, safe, and offers a pleasant experience. The technology used to achieve it does not outweigh the end result, and is certainly not more important than an effective swim curriculum, thoroughly-trained instructors and excellent customer service.

And we also have to weigh other factors, like how hard salt is on metal components in our pools (like the heaters), the fact that we can’t use it for training competitive swimmers who spend lots of time in the water (more than 30 minutes in a salt pool can cause dry mouth) and that the higher amount of dissolved solids in a salt pool means we have to push pumps harder to keep the water fresh.

Trust your nose: The “pool smell” is not chlorine

Speaking of the overall experience, another misconception is that chlorine pools smell. In fact, chlorine itself is odorless – what you might smell at some pools is an odor given off when chlorine oxidizes (or combines with) the contaminants in the pool, and if you smell it, that means either the pool you are at is so dirty it has overwhelmed the system or the location doesn’t have good air circulation.

Since salt pools technically have chlorine in them, as described above, even a salt pool can give off a pool smell. The presence of salt has no effect on the odor. At FOSS, we treat air quality as a separate matter and install top-of-the-line air circulation systems. These, along with our systems to ensure an optimally-clean pool, mean you won’t ever smell a FOSS pool, whether it uses salt or not.

Our final take: Salt is fine, but clean is what matters

In conclusion, we believe salt generators are good as a supplement to pool systems when it the bather load and source water is appropriate. Salt systems alone are perfect for lightly-used pools, like home pools. But as pool filtration and sanitation experts, we don’t think today’s salt technology alone is sufficient to maintain the clean-pool standards at FOSS or other large commercial pools – although we are always following new developments.

Happy swimming, and we’ll see you at the pool!

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