There are three types of pool test kits available to residential pool owners. But for the pool owner concerned about quality water, there is only one to consider – a professional grade DPD pool test kit. We’ll discuss the differences and point you to the best value in pool test kits.
The three tests are OTO, DPD, and test strips. The basic $8 - $10 dollar OTO/PH test kits only test for total chlorine and pH. This pool test kit fails to test for three critical parameters affecting pool water quality. Pool test strip kits are the strips of paper that turn different colors to indicate the level of chlorine, pH or alkalinity of the pool water. Although quick and convenient, they are the least accurate pool test. Test strip kits do not include tests for cyanuric acid or calcium hardness, the two critical parameters in pool water.
A high-quality DPD pool test kit includes tests for pH, calcium hardness, total alkalinity, free chlorine, combined chlorine, pH, and cyanuric acid. We’ll show you the importance of getting a test kit that includes all.
Nearly every pool test kit includes pH. The pH is measured on a scale from 0-14, with a pH of 7 being neutral. Below 7, the water is acidic and above the water alkaline (sometimes called basic). The pH scale is logarithmic, meaning every whole unit increase is 10 times the one before it. pH is of extreme importance in pool water testing. If the pH is too high, sanitizers such as chlorine are rendered powerless against microorganisms. The ideal range of pH is 7.4-7.6. If the pH increases from 7.5 to 8.5, chlorine will lose about 80% of its sanitizing power. At a pH of 9, sanitizers hardly work at all.
Although important, calcium hardness is not included in most pool test kits. The ideal range is 150 – 400 ppm. Water that contains little or no calcium or magnesium is considered soft. Water that contains high levels of calcium and magnesium is considered hard. Calcium may lead to scale, and pool water with no calcium is aggressive and seeks to dissolve calcium from pool surfaces, which may damage finishes over time. We suggest a professional grade test kit that includes calcium hardness.
Every good test kit will include alkalinity. Total alkalinity measures the ability of water to resist changes in pH. It’s the ability to “buffer” water from wide pH swings. A buffer is a chemical system that resists changes upon the addition of acids or bases. In water than contains no buffering ability, pH can wander dramatically. This is called pH bounce – a rapid fluctuation of pH levels with the addition of a small amount of acid, base, chlorine, or any pH-altering agent.
Every pool test kit should include free chlorine. Free chlorine is the workhorse in pool sanitation. Free chlorine is what kills the germs and microorganisms, and keeps your pool safe. At the levels recommended for pools, free chlorine has no detectable taste or smell and does not irritate the skin.
Test kits should always include combined chlorine. Combined chlorine couldn’t be more opposite than free chlorine. Sometimes called chloramines, combined chlorine is formed by the reaction of free chlorine with ammonia wastes from swimmers. Combined chlorine is what causes the vast majority of pool problems such as the foul odor, skin, nose, eye, and throat irritation. Scientific studies have linked combined chlorine to asthma, allergies, and even cancer. Irritation can be noticed in as low as 0.2 ppm. Unlike free chlorine, combined chlorine has very little sanitizing power. The most effective way to decrease combined chlorine is by adding an ultraviolet disinfection system.
Total chlorine is simply the sum of free chlorine and combined chlorine. So if you have the first two, total chlorine is included by default. Although included in most test kits, total chlorine doesn’t tell us much. That’s because we can't determine how much of the total chlorine is combined chlorine and how much is free chlorine. All professional pool test kits have the capability to test all three types of chlorine.
Cyanuric acid, or CYA, should be included in every pool test kit. Cyanuric acid, also called a stabilizer or conditioner, has no sanitizing power. The goal of cyanuric acid is to slow down the depletion of chlorine. Most chlorine sold in big box retail stores today is either dichlor or trichlor. Both of these chlorine types contain significant amounts of CYA. The problem is that CYA levels in pools rarely decrease, but almost always increase. Once the cyanuric acid level reaches 30 to 50 ppm, chlorine’s disinfecting power decreases significantly. Scientific studies have proven that CYA levels greater than 20 ppm provide little benefit over CYA levels of 8-10 ppm. In fact, cyanuric acid levels greater than 50 ppm significantly affect chlorine’s ability to do its job. We recommend a professional pool test kit, and cyanuric acid will be included.
Although you can purchase a test kit for $10 dollars or less, the extra $50 or $75 dollars you’ll spend for a professional grade pool test kit will be money well spent. By keeping the six critical water quality parameters in check, you’ll spend less time and money on chemicals and cleaning, while eliminating many hassles and headaches.