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Before You Begin
The beginning of warm weather means the beginning of pool season! That's when it's time to check your water levels and water quality. Don't panic if you didn't ace chemistry in school—pool test kits are fairly easy to use if you follow the directions. This particular kit, the 4-in-1 by Guardex, tests your pool water's pH, total chlorine, total bromine, acid demand, and total alkalinity.
Other types of kits include test strips or provide analysis through the manufacturer's website, an app or online calculator, or by taking the kit to your pool supply store. Be aware that the bottle numbers, vial sizes, and chemicals in this tutorial are unique to this particular brand of test kit. Follow the instructions for your kit; usually, you can find them online.Continue to 2 of 10 below.
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Just Dip it
Dip the plastic tester into your pool, making sure you draw water from a depth of at least 18 inches for an accurate "catch."Continue to 3 of 10 below.
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Fill to "Fill"
Fill the small vial to the "fill" line with a sample of the pool water.Continue to 4 of 10 below.
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Testing Free Chlorine and Chlorine Residual
Add five drops of solution No. 1, which, in this kit, happens to be ortho-Tolidin, a chlorine indicator.Continue to 5 of 10 below.
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Cap the Vials
Place caps on vials and slowly invert or turn upside down several times.Continue to 6 of 10 below.
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Wait a few seconds to compare the color in the vial with the color standards indicated on the plastic tester to determine the free chlorine level. After that, wait a couple of minutes and compare again to determine the chlorine residual level. Again, check the instructions or test kit website if you aren't sure what to do.Continue to 7 of 10 below.
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Testing the Pool's pH Levels
Fill the large tube to the top, solid line with pool water from a depth of 18 inches. Add one drop of solution No. 4 and mix by gently swirling. This solution is sodium thiosulfate, a chlorine neutralizer. Add five drops of Solution 2, a phenol red indicator, and mix by gently swirling. Compare the color with the pH color standards on the plastic tester. Whatever you do, don’t perform this test if the chlorine residual is above 3.0.Continue to 8 of 10 below.
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Acid Demand Test
Using a sample from the pH test, add the acid demand titrant. Count each drop—making sure to swirl between drops—until the color matches that of the 7.4 indicators. Refer to the acid dosage chart for the correct amount of acid to add to your pool. Whatever you do, don’t perform this test if the pH is above 7.5 and the chlorine residual is above 3.0.Continue to 9 of 10 below.
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Testing for Total Alkalinity
Fill the large tube to the lower dash line. Add one drop of No. 4 and swirl. Next, add one drop of solution No. 5B, a total alkalinity indicator, and swirl. Add No. 3 (count and write down or remember each drop and swirl) until the color changes to clear, light yellow, or light green. Finally, multiply the number of drops of solution No. 3 you used by 10 to determine the total alkalinity. If multiplication makes you uncomfortable, use your smart phone's calculator. Whatever you do, don't perform this test if the chlorine residual is above 3.0.Continue to 10 of 10 below.
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Rinse and Dry
After testing, rinse your plastic tester in a sink (never in the pool), dry, pack up the kit and put it in a cool, dry place, up high away from little hands. Some experts suggest using your test kit weekly during the swimming season.
Don’t buy more pool chemicals than you’ll use in a season, because they can lose effectiveness over time.