Maintaining balanced water is essential when it comes to protecting the integrity of pool/spa structures and equipment. Unfortunately, too many people think that testing the sanitizer and the pH and keeping them at the appropriate levels is all that is required for comprehensive pool water treatment. Well, that’s not the full story! There are actually several other key water quality factors that need to be tested as well: calcium hardness, carbonate alkalinity, total dissolved solids (TDS), and temperature.

When it comes to swimming pools in particular, keeping the pH of the water around 7.4, which is the pH of our eyes and skin, is fundamental. Straying from this pH can lead to eye and skin irritation. Also, if levels are too low, the water becomes corrosive—too high, and the water becomes scaling. The result … damage to your costly investment.

Next, we need to be concerned with the calcium hardness and carbonate alkalinity levels. Keeping these two parameters in check prevents water from becoming aggressive to metals and pool surfaces while also preventing the formation of crusty deposits that are unsightly and can cause a slew of equipment problems. Service technicians need to know a pool’s calcium hardness and carbonate alkalinity levels and adjust them so the water is “balanced”—meaning not corrosive (LSI <-0.3) or scaling (LSI >+0.5).

Although TDS and temperature are not major contributors to water balance, they too should be monitored on a regular basis.

Accuracy Is Not Optional!

Carefully testing for calcium and carbonate alkalinity is a must. Your test equipment needs to be high quality and your testing technique proficient to trust your results and make the necessary changes. Chances are high that you will have problems treating pools if you do not trust your test results.

Calcium does not usually change much over the course of a month, so this parameter does not need to be tested often. Carbonate alkalinity, on the other hand, is affected by bathers, rain, chemicals, and environmental conditions. To properly control carbonate alkalinity, this parameter should be tested weekly. Meanwhile, the technician testing for carbonate alkalinity needs to recognize the part cyanuric acid (CYA) plays on the total alkalinity result found with many drop tests. Much is written in books and taught in classes about CYA contributing to a total alkalinity test result. Knowing the pools CYA level and making the proper adjustment to find the true carbonate alkalinity in waters is critical to achieving balanced water.

A Spectrum of Methods

So which testing method is right for you? Most waters can be controlled with the standard basic liquid reagent test kit. Test strips are becoming more popular, and they are adequate for quick checks of water balance; however, when those test results indicate something is a little “off,” a liquid reagent test kit or a colorimeter will prove indispensable in making necessary chemical adjustments. “The sophistication of the test methods you use needs to be commensurate with the amount of trouble you have with a pool or the value of the facility.” In other words, a pool or spa at a public facility requires a bit more attention than the kiddie pool in the backyard.

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