Pool Chemicals Used to Winterize

The way you use chemicals to prepare your pool for the winter is different than how you use the chemicals during the summer. Because your pool will be covered and out of use for several months, it is imperative that the pool is properly cleaned and chemically balanced before you close it to prevent expensive damage.

Using chemicals to winterize your pool involves several key steps. From adjusting the pH to shocking the pool, no steps should be skipped when adding chemicals to your pool before winter.

Step 1: Adjust the pH

Adjusting the pH should always be the first step when using chemicals to winterize your pool. If the pH level needs to be increased, soda ash can be used. If it needs to be decreased, granular acid can bring it down.

The pH needs to be checked and adjusted again after each step of winterizing your pool with chemicals.

Step 2: Adjust the Total Alkalinity

The total alkalinity should be adjusted between 80 and 120 ppm. This assists the pH and helps it to stay within range for a longer period of time.

The total alkalinity can be increased by gradually adding sodium bicarbonate, and it can be decreased by gradually adding granular acid.

Step 3: Managing the Water Hardness

The amount of calcium in the water determines its hardness. The hardness of the water can affect whether your pool invites lime scale buildup.

To increase the water hardness, use calcium chloride. To decrease it, use sodium bisulfate.

Step 4: Shocking the Pool

To shock your pool, you must add chlorine to the water at a concentration of 3.0 ppm. If your chlorine doesn’t already include a stabilizer, like cyanuric acid, that can be added separately.

Step 5: Adding Algaecide

Adding algaecide is the final step before your pool is chemically ready to close for the season. After shocking the pool, wait until the chlorine level is at 3.0 ppm. If it is any higher, the chlorine will deactivate the algaecide.

Once it has reached that level, add a large dose of algaecide to the water.

For more information on keeping your pool in top shape year-round, so the process is seamless when it comes time to winterize, refer to our infographic, “Creating a Pool Maintenance Schedule.”