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. All target ranges sourced from the CDC Healthy Swimming guidelines and pool industry standards (June 2026).
Target Ranges at a Glance
| Parameter | Recommended Range | Notes |
|---|---|---|
| Free Chlorine (FC) | 1–4 ppm | Test 2× per week; never let drop below 1 ppm |
| pH | 7.2–7.6 | Ideal: 7.4; adjust alkalinity first |
| Total Alkalinity (TA) | 80–120 ppm | Buffer for pH; adjust before pH |
| Calcium Hardness | 200–400 ppm | Low = corrosive water; high = scaling |
| Stabilizer / CYA | 30–50 ppm (chlorine pool) | 60–80 ppm for salt pools |
| Salt (SWG pools) | 2,700–3,400 ppm | Check your chlorinator manual; typically optimal at 3,200 ppm |
| Combined Chlorine (CC) | < 0.5 ppm | Shock when CC ≥ 0.5 ppm (CDC guideline) |
| Total Dissolved Solids (TDS) | < 2,500 ppm (non-salt) | 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. Target 7.4.
- 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.
Wait at least 4–6 hours (ideally overnight) between major chemical additions so each has time to circulate and stabilize before you test and adjust again.
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) 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 (~3–7 years). Keeping salt in the 2,700–3,400 ppm range protects the cell.
- High cyanuric acid (>100 ppm) makes chlorine ineffective even at normal ppm — this is called "chlorine lock." The only fix is dilution.
Seasonal Maintenance Tips
- Opening (spring): Test all parameters before adding any chemicals. Shock first, then balance alkalinity, pH, and calcium.
- 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 | Shock to 20–30 ppm, brush walls, circulate 24 h |
| Stinging eyes | Combined chlorine (CC), pH off | Shock, adjust pH to 7.4 |
| Scaly walls | High calcium or pH | Lower pH, use descaler if needed |
| Faded liners | Very low pH, high chlorine | Balance pH 7.2–7.6; don't over-shock |
| Salt cell error | Salt too low/high, CYA >100 ppm | Adjust salt, dilute to lower CYA |
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 at least twice per week during swim season. 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 1 ppm), 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). Target is −0.3 to +0.3. Use it as a diagnostic when standard ranges look correct but water still has problems.