A Deeper Dive – Using your Test Kit to Improve Swimmer Experience and Reduce Costs

Your test kit is the key to clear water, happy swimmers, effective chemical usage and a protected pool structure. Don’t let those reagents sit unused. Follow us on a guided tour through the typical test kit.


Chlorine / Bromine – This is the easy one. Measuring, monitoring and controlling your sanitizer is the best way to rid your pool of harmful pathogens. They key here? Test often. Sanitizer levels can change quickly. You want to make sure that you’re always meeting state minimums, without having levels so high that you’re impacting bather comfort.

pH – The next tool in your test kit measures the pH of your water on a scale of 0-14 (very acidic, to very basic). Your pool should exist near the middle, ideally with a pH of 7.4-7.6. At this level swimmer comfort is optimal and you’re efficiently able to utilize various types of chlorine or bromine as your sanitizer.

Alkalinity – Think of alkalinity as pH’s anchor. Proper alkalinity makes it easier to control your pH. If your alkalinity is too high, your pH locks up and becomes difficult to change. If your alkalinity is too low, your pH fluctuates or “bounces” outside of your control. Remember, alkalinity impacts pH, and pH impacts your efficient sanitizer usage. In other words, alkalinity, pH and chlorine control are so closely related that if you’re not checking alkalinity regularly, you’re likely spending too much money on pool chemicals.

Calcium Hardness – Water seeks out calcium and will find it in your pool structures. Walls, grout lines, tiles and heater elements can all become quick targets of hungry water. It’s best to feed your pool the calcium it wants before you compromise the structural integrity of your pool. Ideally for pools, calcium hardness will be 200-400 ppm (lower for warmer bodies of water). If your calcium is too high, you’ll need to drain water down and replace with fresh water. Dilution is the only way to lower high calcium levels which can contribute to scale formation and cloudy water conditions.

Total Dissolved Solids – What else is in your water that we may not have considered? A TDS test can determine other dissolved components. These often come from high bather loads, source water and specialty chemicals. Many pool test kits do not contain a TDS meter – you may need to buy one separately. TDS will contribute to your pools balance (discussed below) and is important to track.

Saturation Index – When you consider pH, Alkalinity, Calcium Hardness, TDS and Temperature together, you can determine if you water is balanced, corrosive, or scale forming. This number is called the Saturation Index. Determining your SI is a simple process. Factors for each test are entered into a simple formula and the end number falls onto a range. A number outside of the ideal range suggests that one or more of the factors of the SI must be changed to achieve balanced water conditions. Some test kits contain a basic slide calculator that can simplify the process of determining your Saturation Index.

Cyanuric Acid – If you’re adding a stabilizer to your pool, or using a stabilized chlorine, you’ll want to regularly check your CYA levels. Stabilizers can be helpful in warmer environments at outdoor pools with extended season and lots of sun exposure. Under those conditions, stabilizers can reduce the dissipation of chlorine associated with UV exposure from sunlight. If CYA levels are higher than their ideal range, they do not allow chlorine to oxidize and disinfect properly. This condition is dangerous to swimmers and should be routinely monitored. If CYA levels are too high, water must be diluted before safe swimming can resume.

Salt – If you’re running an in-line chlorine generator, your pool relies on a level of salt dissolved into solution to produce chlorine on-site. Testing salt regularly assures this process works as-designed. Although salt is recycled in this process, additional salt may be needed to replace salt content lost in splash-out, backwashing, vacuum discharge or leaks.

Testing Frequency – When it comes to water monitoring, some chemical balance components need to be checked more frequently than others. When determining the frequency of your testing, start with your state and local codes. At a minimum, you need to test as frequently as required, but you may benefit from checking more often. Chlorine and pH values typically fluctuate quicker than calcium and alkalinity, so you would be wise to check them more often. Calcium levels, total alkalinity, cyanuric acid and salt should be checked more frequently at the beginning of the season, or after a major drain and fill process. Once you have a general idea of how quickly they fluctuate, and know if their levels are generally rising or falling, you may be able to reduce your testing frequency.

Following Instructions – The best advice on your test kit usage comes directly from the manufacturer. Take the time to read your entire test kit manual to understand the process, science, application and common mistakes made when testing. Your increase in knowledge will lead to a better swimmer experience and reduced operating expenses.

Chemical testing is discussed in-depth at all Aquatic Council CPO courses. For the most up to date schedule of available classes, click here.