Pool Water Balance Guide
Balanced pool water is safe to swim in, gentle on equipment, and clear. This guide covers target ranges for every key parameter, the correct order for chemical adjustments, and how to troubleshoot the most common problems. Free chlorine targets follow poolchemcalculators.com; pH targets follow the Model Aquatic Health Code (MAHC). Total alkalinity 80–120 ppm per poolchemcalculators.com; calcium, CYA, and salt ranges cite the linked references in the table below.
Target Ranges at a Glance
Quick reference — see the table for every target range; test chlorine and pH regularly during swim season.
| Parameter | Recommended Range | Notes |
|---|---|---|
| Free Chlorine (FC) | 2 ppm recommended per poolchemcalculators.com; 3 ppm maximum for regular use | 1 ppm minimum safe level; shock higher when needed |
| pH | 7.2-7.8 per MAHC | Adjust alkalinity first; retest within range |
| Total Alkalinity (TA) | 80-120 ppm per poolchemcalculators.com | Buffer for pH; adjust before pH |
| Calcium Hardness | 200-400 ppm plaster/concrete per poolchemcalculators.com; 150-250 ppm vinyl/fiberglass per poolchemcalculators.com | Low = corrosive water; high = scaling |
| Stabilizer / CYA | 30-50 ppm per SwimUniversity (chlorine pool) | 60-80 ppm for salt pools per SwimUniversity |
| Salt (SWG pools) | 2700-3400 ppm per Hayward | Optimal at 3200 ppm per Hayward; check your chlorinator manual |
| Combined Chlorine (CC) | Keep below 0.4 PPM per MAHC | Shock when combined chlorine exceeds 0.4 PPM per MAHC |
| Total Dissolved Solids (TDS) | Keep below ~2,500 ppm for non-salt pools per Orenda | Partial drain/refill if high |
Chemical Adjustment Order
Always adjust in this sequence to avoid compounding problems:
- Total Alkalinity — Use baking soda to raise; muriatic acid to lower. See the alkalinity calculator.
- pH — Use sodium carbonate (soda ash) to raise; muriatic acid to lower. Stay within the MAHC 7.2-7.8 pH range.
- Calcium Hardness — Use calcium chloride to raise; partial drain to lower.
- Sanitizer — Add chlorine, liquid chlorine, or verify salt level. See the salt calculator, chlorine calculator, and shock calculator.
- Stabilizer (CYA) — Add cyanuric acid only if below target. See the CYA calculator.
After raising alkalinity, wait about 24 hours before adjusting pH (poolchemcalculators.com alkalinity guide). Allow several hours between other major additions so each can circulate before retesting.
Salt Pool vs. Chlorine Pool: Key Differences
- Salt pools still use chlorine — the salt cell generates it by electrolysis. Free chlorine targets are the same.
- CYA target is higher for salt pools (60-80 ppm per SwimUniversity) because the chlorinator runs continuously and chlorine degrades faster in direct sunlight.
- Salt does not evaporate. You only need to add salt after significant water loss (drain, backwash, heavy rain overflow).
- Salt cells have a finite lifespan — check your chlorinator manual for replacement intervals. Keeping salt in the 2700-3400 ppm Hayward range protects the cell.
- Per SwimUniversity, very high cyanuric acid can make chlorine less effective — dilution is the usual fix.
Seasonal Maintenance Tips
- Opening (spring): Test all parameters before adding any chemicals. Balance alkalinity, pH, and calcium first, then shock if sanitizer is low.
- Peak summer: Test chlorine and pH 2–3 times per week. After swim parties or storms, shock and retest.
- Closing (fall): Balance all chemistry, add winterizing algaecide, and lower water level below skimmer. Drain pumps and filters per manufacturer instructions.
Common Problems and Fixes
| Problem | Likely Cause | Fix |
|---|---|---|
| Cloudy water | Low FC, high pH, algae | Shock, lower pH, run filter 24 h |
| Green water | Algae bloom | Use algae/problem shock dosing, brush walls, circulate 24 h |
| Stinging eyes | Combined chlorine (CC), pH off | Shock, adjust pH into MAHC 7.2-7.8 range |
| Scaly walls | High calcium or pH | Lower pH, use descaler if needed |
| Faded liners | Very low pH, high chlorine | Balance pH within MAHC 7.2-7.8 range; don't over-shock |
| Salt cell error | Salt too low/high, very high CYA | Adjust salt, dilute to lower CYA per SwimUniversity CYA guidance |
Calculator Links
- Pool Salt Calculator — how many pounds of salt to add
- Pool Volume Calculator — gallons by pool shape
- Pool Shock Calculator — cal-hypo dosing
- Pool Chlorine Calculator — liquid chlorine dosing
- Pool Alkalinity Calculator — baking soda dosing
- Pool Stabilizer Calculator — CYA dosing
Frequently Asked Questions
Follow this order: (1) Alkalinity, (2) pH, (3) Calcium hardness, (4) Sanitizer (chlorine/salt), (5) Stabilizer (CYA). Alkalinity is adjusted first because it buffers pH — fixing it first reduces how much pH adjustment is needed.
Test free chlorine and pH regularly during swim season — keep chlorine at 2 ppm recommended per poolchemcalculators.com (1 ppm minimum safe level). Test alkalinity, CYA, and calcium hardness every 1–2 weeks, or after a heavy rain, large bather load, or chemical addition.
Cloudy water is usually caused by low sanitizer (FC below the 2 ppm recommended target per poolchemcalculators.com), high pH, high alkalinity, high calcium hardness, or algae in early stages. Shock the pool, check pH and alkalinity, run the filter 24 hours, and backwash if needed.
LSI is a formula that combines pH, temperature, calcium hardness, alkalinity, and TDS to calculate whether pool water is corrosive (negative LSI) or scale-forming (positive LSI). Per TFP's CSI/LSI guide, balanced water falls in the -0.3 to 0.3 range. Use it as a diagnostic when standard ranges look correct but water still has problems.