How Often to Add Chlorine to a Pool

Keep free chlorine between 1–3 ppm. How often you add it depends on testing, weather, and use. Use our Pool Chlorine Calculator for the right amount when you do add.

Testing frequency

• Test chlorine (and pH) at least 2–3 times per week.
• In hot weather or heavy use, test daily.
• After rain or a party, test and add chlorine if needed.

When to add chlorine

Add chlorine whenever the test shows below 1 ppm. Tablets in a floater or skimmer add a steady amount; liquid or granular is for boosting or shock. Don’t wait for the water to turn green—keep it in range consistently.

When to shock

Shock (raise chlorine high for a short time) after heavy use, rain, or when chlorine won’t hold. Use our Pool Shock Calculator. Run the pump for several hours and don’t swim until chlorine is back to 1–3 ppm.