Pool Chemical Guide: How to Balance Your Pool Water

Essential Pool Chemistry Parameters

Free Chlorine: 1–3 ppm (parts per million). Primary sanitizer. Below 1 ppm, algae and bacteria growth accelerates. Above 5 ppm, irritates eyes and skin.
pH: 7.4–7.6. Below 7.2: corrosive to equipment and eyes. Above 7.8: chlorine becomes ineffective (at pH 8.0, chlorine is 22% effective vs. 75% at pH 7.2).
Total Alkalinity (TA): 80–120 ppm. Buffers pH against rapid swings. Low alkalinity causes pH to "bounce" wildly.
Cyanuric Acid (stabilizer/conditioner): 30–50 ppm for outdoor pools. Prevents UV from breaking down chlorine. Essential for outdoor chlorine efficiency.
Calcium Hardness: 200–400 ppm. Too low causes water to leach calcium from surfaces (plaster pitting). Too high causes scale.

Testing and Adjustment Order

Always adjust in this order: (1) Total Alkalinity, (2) pH, (3) Calcium Hardness, (4) Cyanuric Acid, (5) Chlorine. Adjusting TA first makes pH adjustment more predictable. Allow 4–6 hours between major chemical additions and retest before adding more.

Weekly Maintenance Routine

Test and adjust chlorine and pH (most frequently needed)
Check TA and adjust monthly or as needed
Shock the pool weekly during peak season (after heavy use, rain, or algae signs)
Clean skimmer baskets and pump strainer weekly
Brush walls and floor weekly to prevent algae attachment

Frequently Asked Questions

How do I raise pool pH?

Add soda ash (sodium carbonate) to raise pH. Start with 6 oz per 10,000 gallons for a 0.2 pH increase. Dissolve in water before adding. To lower pH, add muriatic acid or sodium bisulfate. Add acid near a return jet with the pump running. Always add acid to water (not water to acid) and wear gloves and eye protection.

What causes green pool water?

Green water is almost always algae, caused by insufficient chlorine, high pH (making chlorine ineffective), or both. Remedy: shock the pool with 2–3× normal chlorine dose, brush all surfaces, run the pump 24 hours, vacuum dead algae. Test and correct pH (must be 7.2–7.6) before shocking. Severely green pools may need multiple shock treatments over 2–3 days.