The Top 10 Testing Techniques for Pools and Spas

What am I doing wrong? I never saw THAT color before! It didn’t turn pink. Purple?? Nobody said anything about purple! Do I hold the bottle straight up and down or sideways? Are my reagents still good after two years? How many drops do I add?

So many questions and, unfortunately, so little time to get the answers when you have to visit 20+ pools a day for service and testing. It’s a fast-paced world out there, and not having a 100% level of confidence in your testing abilities only increases the problem.

If you’re a new service tech with little or no experience, you often rely on the so-called expertise of other employees who’ve “been around the block.” All sorts of stories, rumors, shortcuts, tricks, and advice are given by these mostly well-meaning veterans. However, more often than not, the information they are giving you is … well … wrong.

So to dispel any misinformation, here’s a list of the top-10 techniques we recommend for obtaining accurate, reliable test results:

1. Read the Instructions! Don’t assume you know how to do the test, especially if you switch test kit manufacturers. Not all instructions are the same! And if you purchase a new kit from the same manufacturer, it is always best practice to review the instructions to see if anything has changed. The same applies to test strips, which can have different directions from manufacturer to manufacturer.

2. Take a good representative sample (at elbow depth: 18" or 45 cm) below the surface of the water and away from the return line since the concentrated/treated water in that area will not be representative of the water in the entire pool or spa. Use a clean, plastic container to collect the sample. When using test strips, never dip the strip directly into a pool or spa, which could produce erroneous test results. Instead, collect a sample as described above, and then dip the strip into the sample.

3. Use the correct sample volume. When filling a sample tube with water you may see a curve at the surface of the water. This curve is called a meniscus. When holding the sample tube at eye level, the bottom of this curve should rest on the appropriate fill line for the test.

4. Don’t interchange reagents between different test kit manufacturers. Reagents are created based on a number of different parameters such as sample size, view depth, drop equivalence, etc. Just because a reagent has the same name, doesn’t mean it’s the same strength.

5. Always hold dropper bottles straight up and down when dispensing drops of reagent. Holding the bottle at an angle (or sideways) will distort the drop size, creating a false-high result. This is especially true when testing for total alkalinity or calcium hardness.

6. Don’t use your fingers or the palms of your hand to cover a test vial while mixing. Even though you think your hands are perfectly clean, there are natural oils on your skin that may affect the results of your testing. Use the caps that come with the test kit.

7. NEVER shake a sample to mix the reagents unless the instruction specifically says to do so. Shaking can actually produce a false test result. To mix properly, simply invert the sample cell a few times.

8. Don’t wait to match colors unless the instructions require a wait time. Some reagents (those that are in a brown opaque bottle) are natural oxidizers and will react quickly with heat, air, and sunlight.

9. Follow the “endpoint + one drop” rule when performing drop tests to make sure you’ve reached the correct endpoint. In other words, if you’re not sure that the endpoint color is correct, add one more drop. If it didn’t change color, then the previous drop was enough and record that as the total number of drops used. If the sample continues to change color, keep on adding drops until the sample stops changing color.

10. Use the proper light source for color matching! The best light to use for any color-matching test is natural sunlight. Position yourself with the sun on your back or over your shoulders — DO NOT FACE THE SUN. Facing the sun will alter your eye’s ability to match colors. Remember to hold the comparator block eye level and perpendicular to the ground (don’t tilt).

We invite you to join Wayne Ivusich, Taylor’s Director of Education, for his free webinar series, which includes a webinar on Testing Techniques. Learn how to hone your testing techniques to obtain accurate, reliable, and consistent readings for all your testing situations. Go here to register for our webinars: https://www.taylortechnologies.com/en/content/training-seminars