water testing
Photo: Craig Raine
Maintaining proper pH and chlorine levels is vital to ensuring that pool water is kind to both equipment and swimmers. Fluctuating pH is one problem: Levels lower than 7.2 (too acidic) may dissolve plaster or concrete surfaces and cause metal in the mechanicals to corrode. Higher levels reduce chlorine's ability to kill microorganisms, such as E. coli or those that cause ear infections and rashes.

Chlorine monitoring is equally important. “If you don't watch the levels, you risk exposure to harmful bacteria,” says Dr. Thomas M. Lachocki of the National Spa & Pool Institute (NSPI). At the same time that chlorine destroys bacteria and algae, it bonds with nitrogen-based ammonia — largely from urine, fertilizer, and the environment — forming bothersome chloramines. It's chloramines — not excessive chlorine — that sting the eyes and irritate the skin. Paradoxically, adding more chlorine destroys the chloramines. However, excessive chlorine — the NSPI's standard is a maximum of 10 ppm — can not only irritate mucous membranes but corrode system parts and fade your swimsuit.

Still, chlorine remains the industrywide favorite: As long as you're vigilant, checking levels once a week and more frequently during peak usage, it's a safe and very effective sanitizer. The only thing better might be to boil the water.
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