So, you’ve finally got that swimming pool or hot tub all set up, and you’re ready to dive into that sparkling water. Hold your inflatable horses. Just because the water looks good doesn’t mean it’s actually safe for swimming. Luckily, pool and spa test kits make it simple to check that your pool’s water chemistry is just right. It’s important to test your water every week and also every time you add water or chemicals to the pool.

Top Pick

This kit measures pH and total chlorine plus four other water components— free chlorine, alkalinity, total hardness and stabilizer—at once. Clorox

For maintaining a clean, healthy pool, the most vital measurements are chlorine level and pH. Chlorine keeps algae, bacteria and other microbes in check, so low chlorine levels mean the water can become cloudy and unsanitary. Too much chlorine can signal problems for your lungs and skin, and cause your pool components to break down. The pH measurement tells you how acidic the pool water is: readings below 7 are acidic and above 7 are alkaline. Ideally, you want the pH of the water to match the pH of your eyes and mucus membranes—a slightly alkaline 7.4.

Good for Newbies

With this kit, simply dip the indicator and you’re done! JR.WHITE

Test strips make water testing super simple by reducing the chemical reactions to a single, ready-to-dip strip. For best results, collect the water sample from the absolute center of your pool water by holding a clean cup upside down, lowering it elbow-deep into the pool, then flipping the cup right-side up and lifting it out. Then, dip the strip and allow it to air dry for about 15 seconds before comparing the colors on your strip to the colors on the kit label.

Total Bargain

This option includes two reagents and a collection vial for measuring the most vital components of your H2O chemistry. U.S. Pool Supply

If you choose to go a more traditional route, a non-strip testing option includes a two-channel test vial and a pair of reagents. Once you add the correct amount of pool water to each channel, add 5 drops of the chlorine reagent (orthotolidine, or OTO) to one side and 5 drops of the pH reagent (phenol red) to the other—then compare the resulting water color to the chart. Redder water indicates higher pH, and brighter yellow water represents higher chlorine levels. You can view the colors most accurately if you hold the vial up to a white background.