Scoop chlorine granules into water in a nonmetal container, following package directions. Always wear goggles and rubber gloves when handling chlorine, and always put the chlorine into the water–don’t pour the water over the chlorine.

Stir for about 30 seconds, and leave for 30 minutes to settle.

Turn on the filter. Reaching as far into the middle of the pool as possible (perhaps by standing on a diving board), pour the chlorine into the pool. Discard any sediment left in the container.

Add chlorine three to four times a week for a pool in heavy use.

Occasionally–no more than once a week–you may need to superchlorinate (also called shock) the pool to burn any built-up bacteria, algae and ammonia. Following chlorine package directions, make a solution for superchlorination (it will be three to five times as strong as normal chlorine).

Add the chlorine solution to the pool after sundown, if possible, as the sun’s rays break down chlorine.

Before allowing anyone to go in the pool, test the residual chlorine level to make sure it has gone back down below 3.0 ppm. This will take at least several hours.