The basic job of a pool and spa service professional is to ensure that their customers’ water is adequately circulated, sanitized, and balanced. Taken together, these three actions prevent algae, prevent disease, and prevent degradation to equipment and surfaces.

Adequate circulation and filtration is generally a set-it-and-forget-it action. There’s not much to it beyond regular filter cleanings and emptying baskets. But ensuring adequate sanitation and balance requires regular testing, which is the topic of this issue of Service Industry News.

Clearly, accurate results rely on an accurate test kit. Look for one that allows you to test for free chlorine, combined chlorine, pH, total alkalinity, calcium hardness, and cyanuric acid. Be sure that the chlorine test uses a FAS-DPD kit, which measures chlorine levels up to at least 25 ppm with an accuracy of .2 ppm. It does not undergo bleaching out like the DPD test does and is very easy to read because the color change is from red to colorless.

Once you are satisfied with your test kit, there are a few things that you must keep in mind to continue obtaining accurate results.

Nearly all manufacturers recommend beginning the season with fresh reagents. Cynics may believe that this is so manufacturers can make more sales, but the fact is that reagents are perishable, with active ingredients that decompose over time. Extremes of heat, as well as exposure to humidity, air, sunlight, or other chemicals diminish their useful life.

Be sure to keep it clean — keep reagent bottles capped tightly and take care never to mix up caps.

Wash test cells well after use to prevent cross contamination and cell staining.

Replace any broken, stained, or cloudy test cells. You won’t get accurate results if the test cell itself interferes with the test. Also, replace faded color standards.

When you do replace reagents or testing equipment, don’t interchange between different manufacturers. Each manufacturer formulates their reagents in different concentrations, and color standards are specific to those concentrations. Similarly, test cells of different volumes and path lengths influence the concentration that is being measured.

Read the manufacturer’s directions carefully before beginning each test.

For example, if the test strips instruct you to dip the strip and read the result immediately but you dip and hold in the water for 15 seconds, the color development will be compromised.

Similarly, if the instructions on a pH drop test advise you to swirl the sample after each drop, and you decide to shake the sample vigorously, you could alter the pH you’re trying to measure.

Be sure to test the sample immediately so that conditions don’t change.

Try to work with a sample that is representative of the pool as a whole. Experts recommend drawing a sample from mid-depth of the pool from at least elbow length.

Water taken from too near the surface may contain oils and debris. Water taken near returns and chemical feeders may contain higher than average sanitizers.

Water taken from corners may not be as mixed as that from open areas of the pool. We are trying to get a sense of the average chemical levels of the pool — not the atypical conditions.

Be sure to conduct color-based tests in natural light. Color perception is based on lighting, and artificial light can make it difficult to perceive color variation. And don’t wear sunglasses.

Look for additional articles related to pool and spa chemical testing in this issue of Service Industry News.