- The pool water pH should be adjusted to within 7.2 to 7.6. Alkalinity should be in the range of 80 to 120 parts per million, and calcium hardness around 180 to 220 ppm. The pH can be adjusted by adding muriatic acid or sodium bisulphate to lower it, or adding soda ash to raise it. Sodium bicarbonate or muriatic acid can be used to balance the alkalinity. Calcium chloride addition will increase hardness, and sequestering agents can be added to lower it.
- Perform one last chlorine shock to keep the pool water clean during the down time. A stabilized granular chlorine product such as dichlor is recommended. A non-chlorine shock such as potassium monoperfulfate is another option.
- A high-strength algaecide should be added to prevent algae growth in the water during wintering. Special winterizing algaecide preparations with longer lasting action are available. Do not add algaecide immediately after the shock, since the high chlorine levels will attack the algaecide.
- Although it is optional, it is usually advisable to add a portion of metal sequestering agent to the pool as a final step. This will bind metals such as iron that might otherwise stain pool areas during the shut down period.
pH and Alkalinity
Shock
Algaecide
Metal Sequestering
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