Pool Chemistry Basics

Keeping your pool water balanced protects swimmers and equipment. Here are the key parameters.

Chlorine

Chlorine sanitizes the water and kills bacteria and algae. For swimming pools, keep free chlorine between 1–3 ppm. Test 2–3 times per week and add chlorine as needed. After heavy use or rain, you may need to shock the pool.

pH

pH measures how acidic or basic the water is. The ideal range is 7.2–7.6. Low pH can damage equipment and irritate skin; high pH can cause scaling and reduce chlorine effectiveness. Use pH increaser (soda ash) or pH reducer (dry acid) to adjust.

Total Alkalinity

Alkalinity (80–120 ppm for most pools) acts as a buffer for pH. If alkalinity is too low, pH will swing easily. If it's too high, pH can be hard to lower. Adjust alkalinity before making large pH changes.

Testing

Use test strips or a liquid test kit. Test chlorine and pH frequently; test alkalinity and other parameters weekly. Record results and adjust chemicals based on your pool volume—use our Chemical Calculator for dosing.

Quick Tips

• Run the pump when adding chemicals and allow 20–30 minutes before re-testing.
• Never mix chemicals; add them separately.
• Store chemicals in a cool, dry place and follow label instructions.