Freezing temperatures don’t just challenge outdoor comfort — they can also impact your pool and spa water testing routine. Colder water temperatures can alter reaction times, solubility, and may even disrupt the efficacy of test reagents. From skewed alkalinity and calcium hardness readings to pH tests that yield faded or inaccurate results, frigid conditions can contribute to frustrating false readings.
For example, it may take a few more drops of reagent in a total alkalinity or calcium hardness drop test before you see the color change, resulting in a false-high reading. In a pH test, some reagent components may precipitate when the reagent is added to a low-temp sample, causing faded test colors, inaccurate results or no reactions at all! It’s also widely known that CYA testing of low-temp water will provide false-low test results (even at water temperatures in the 60s) because the speed at which the precipitate forms is slowed down tremendously. Other tests could be affected as well.
Temperatures of <45°F (7.2°C) can affect color development for test strip users. As a general guideline, Taylor recommends not testing pool/spa water samples that are <45°F (7.2°C). Another important reminder: Always store reagents and test kits in a temperature range of 36°F to 85°F (2.2°C–29°C). For those of you who use meters, you’ll be happy to know that low-temperature samples do not usually affect test results (but it’s wise to verify this by checking your meter’s specifications).
So, what do you do when temps drop and you need to test your pool water? If you must test pool/spa water <45°F (7.2°C), collect the sample from 18″ below the surface in an opaque container. Bring the collected sample inside to a warmer environment, then wait a few minutes before performing the test.