The Truth About Water Testing

Spring pool openings mean water testing. But, before you reach deep into that awful green fluid lingering beneath your winter cover, there are a few important items you need to consider.

Rule #1: Old condiment, zip lock baggies, or pickle jars do not make the best water sample bottles

Professional pool stores sell proper water sample bottles. Stop by your local swimming retailer and invest in an actual water testing bottle. It’s the perfect size for the amount of water necessary for testing, and it has been sterilized to permit correct readings and solutions.

Rule #2: The water needs to have been circulating in a pool at least 24 to 48 hours before testing can take place.

This is the most misunderstood spring water testing rule, and the most important one to follow. Countless pool owners anxiously wait in line for their water to be tested, only to be told that their test does not provide true results.

The Simple fact is that water needs to be turned over in the swimming pool several times to ensure a good mixing has happened. Stagnant water tends to form into layers, or stratify; therefore, an unmixed sample will not accurately reflect the entire pool water chemistry.

Rule #3: Reach down at least 16” under the surface of the water and away from returns to pull the sample.

It’s always been a good practice to go deep to gather a sample. The recommended depth is 16” or about elbow length. As water stratifies, a sample taken from the surface will yield a completely different reading than that of deeper water.

You also don’t want to pull the water sample near the pool’s return. Returning water typically has a much higher concentration of sanitizer (chlorine) than the entire body of water. Water samples pulled from an area close to the return are not similar to the entire pool’s water chemistry. As a rule of thumb, the further away from the return the better your results will reflect your pool chemistry.

Rules #4: Temperature DOES affect several water testing categories.

Your best testing results occur when a sample is obtained in water temperatures between 70-80⁰F. For example, Cyanuric Acid (stabilizer) tests will results in higher readings when pool temperatures are cold and lower readings when warm. You don’t want to commence with a partial draining of your pool because a 50⁰F water sample said you had high CyA levels. Before taking drastic or unnecessary steps, let your water reach a suitable temperature for correct analysis.

Rules #5: Do not leave your water sample bottle at the store.

This is undoubtedly the single and most common mistake made by pool owners across North America – forgetting their water sample bottle at the store’s testing counter. Your water sample bottle is the most important instrument in your pool toolkit. Don’t leave it behind.

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