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“Mommy, my eyes don’t hurt!”

My ten-year-old had just finished a three-hour session in a neighbor’s pool and, lo and behold, her eyes were not red, not stinging. “It’s because I have a saltwater pool,” said my neighbor. “I make my own chlorine. Their hair doesn’t turn green, either.” Curious, I called Aaron Ryan at Pool Time (619-977-8976; sdpooltime.com) to learn more.

“As far as sanitizing a pool,” he begins, “you’ve got several parameters you look at. The first thing you want to balance is your pH — you want it somewhere between 7.2 and 7.6. You adjust it by adding either soda ash or muriatic acid. San Diego water is very acidic, and if you don’t balance it, your chlorine won’t work like it should. If your pH is above 7.6, even if you add a bunch of chlorine, it’s going to disappear in a matter of hours. After that, you want to dial in your alkalinity and then you can go ahead and add your chlorine. You can use granular chlorine, liquid chlorine, or tablet chlorine that sits in a floater in your pool. I like tablets because they last longer, especially in the summertime. That’s because the tablets also contain a chlorine stabilizer that keeps them from being degraded by the sun’s rays. I use them on all my pools that don’t have salt generators.”

And what about those salt generators? “It’s a mini chlorine generator. You add anywhere from five to ten 50-pound bags of salt to your pool, and then you plumb the chlorine generator into your PVC line. Inside the generator are steel plates coated with tungsten. When you pass the saltwater in between those plates and add an electrical current, that gives you chlorine.”

The first advantage of such a system, says Ryan, is that “the water will feel softer. It’s better for your hair, your eyes, skin, nails, all that good stuff. If your pool guy is doing it right, the water will be less salty than the tears in your eyes, so it shouldn’t feel salty to the eye.”

More pluses: “You have a constant chlorine level, without a lot of spikes and valleys.” This means that there is less chance of algae getting started during the chlorine’s low point or a swimmer suffering stinging eyes during a chlorine spike. “Also, the electrical current gets rid of chloramines. When you smell chlorine, you’re not actually smelling chlorine; you’re smelling what’s called chloramines. It’s your body’s oils, ammonia, stuff like that, all mixed with the chlorine. That’s what produces that smell. The electrical current gets rid of it.”

But, says Ryan, it’s not all good news. “The constant generation of chlorine produces water with a higher pH, so you have to add muriatic acid each week to bring the pH down. It actually costs a little bit more than adding chlorine to the pool. And you still might have to add a little chlorine sometimes” — such as after a heat wave that burns off more chlorine than your system is generating. “You shock the water with the additional chlorine and then adjust your system’s output upwards. And you have to run your pump more than you would if you used tablets — maybe two hours more a day. Oh, and you get calcium buildup on the cell, and you need to do an acid wash on it once a year. I charge my clients $55 each time.”

The up-front cost for a cell is $700–$1000, plus $150–$300 for installation. The cells last three or four years and cost $500–$600 to replace.

After talking to Ryan, I was torn — the pluses were nice, but the minuses did pile up. I put in a call to Alison Osinski at Aquatic Consulting Services (619-602-4435; alisonosinski.com) for more information.

“Calling them saltwater pools is nonsense,” she begins. “It’s a chlorinated pool that happens to have salt in it. There is no difference between the chlorine you make and the chlorine you buy. Also, as soon as you put saltwater into a pool, you’re causing all kinds of other problems related to the longevity of equipment and surfaces. Everything is going to deteriorate faster. I prefer offline systems — a container with a diaphragm between distilled water and brine solution.” The chlorine is generated in the offline container. “You still have a potable-water pool, and you just dump in chlorine.”

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Comments

JeffSloan April 8, 2010 @ 11:27 a.m.

Thanks for clarifying that “salt water pools” are still disinfected with chlorine. Regardless of how it gets there, chlorine is essential for protecting against germs that can make swimmers sick. It was also helpful to point out that the irritating smell from poorly maintained pools is actually caused by chloramines.

However, I am not aware of any documented basis for the comment that chlorine generators “get rid of chloramines.” Maintaining proper chlorine levels is important. But the best way to control chloramines is to keep contaminants out of the pool in the first place. Swimmers can help by showering first and (do I really need to say this?) never peeing in the pool.

Also, chlorine doesn’t turn your hair green— that’s actually caused by copper, which is sometimes used to prevent algae growth.

Best, Jeff

Jeff Sloan American Chemistry Council

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