Water—and especially heated water—is a breeding ground for algae and other micro-organisms that carry disease. For this reason, sanitizing your pool water on a regular basis is essential to pool maintenance. The traditional method of sanitization is the use of chlorine, which not only eliminates bacteria but is also able to break down organic debris through oxidation.

Chlorine comes in liquid form, though this is not commonly used for home pools; granular form, which is dissolved before being added to pool water; and tablet form, placed in a floating feeder that slowly dissolves and then releases the chlorine into the pool. The chlorine, in reaction with the pool water, produces hypochlorous acid, or what is called “free chlorine,” which is actually what sanitizes the water. But, free chlorine degrades rapidly in sunlight, so cyanuric acid, which stabilizes the compound, is added with the chlorine.

After treating your pool water with chlorine, you will have to check its level regularly to see if you need to add more. Test kits are readily available at pool-supply stores. (A kit that also measures pH and calcium levels, plus alkalinity, is recommended.) Your free chlorine level should be 1–2 parts per million (ppm). The amount of chlorine you may need to add depends greatly on your pool use; expect to add chlorine daily during the heavy-use summer months.

Always follow label directions to the letter, and never mix more than one type of brand. Chlorine compounds can be corrosive, to your pool and to you. As your will have to handle the chemical by hand, make sure to wear proper protection on your hands and face.

If you are using the granular form, mix it by adding it to water and not the other way around to ensure it does not splash on you. Pour the solution into the pool in several different places, as close to the surface as your can. The tablet form is simply added to the feeder.