Pool Water Chemistry Calculator
Enter your pool size and current test readings. Get exact chemical dosing instructions to bring every parameter into balance.
Pool chemistry target ranges
Keep all six parameters in balance. Correcting one often affects the others — always address alkalinity before pH, and pH before chlorine.
| Parameter | Target range | Ideal | Why it matters |
|---|---|---|---|
| Free Chlorine | 1–3 ppm | 1.5–2 ppm | Sanitizes the water and kills bacteria, algae, and pathogens. |
| pH | 7.2–7.6 | 7.4 | Controls how effective chlorine is and prevents equipment corrosion and swimmer discomfort. |
| Total Alkalinity | 80–120 ppm | 100 ppm | Stabilizes pH so it doesn't swing up and down between service visits. |
| Calcium Hardness | 200–400 ppm | 250–300 ppm | Prevents water from etching plaster or depositing scale on surfaces and equipment. |
| Cyanuric Acid (CYA) | 30–50 ppm | 40 ppm | Protects chlorine from UV degradation in outdoor pools. Not needed for indoor pools. |
| Salt (saltwater pools) | 2,700–3,400 ppm | 3,200 ppm | Feeds the salt chlorine generator to produce chlorine continuously. |
Chemical safety tips
Add one chemical at a time
Wait 4–6 hours (one full pump cycle) between additions so you can accurately measure the effect before adding more.
Never mix chemicals
Adding two chemicals to the same bucket or skimmer — even sequentially — can cause dangerous reactions. Always use separate locations.
Add chemicals to water
Pre-dilute chemicals by adding them to a bucket of water, not the other way around. This prevents splashing and hot spots.
Test at the right time
Test water after the pump has run for at least 1 hour for an accurate reading. Mid-afternoon gives the most consistent results.
Adjust alkalinity first
TA is the buffer that holds pH steady. Correct it first — pH often corrects itself afterward, saving chemicals.
Wear protective gear
Always wear chemical-resistant gloves and eye protection when handling pool chemicals, especially muriatic acid.
Frequently asked questions
How accurate are the dosing amounts?
Amounts are based on standard industry formulas and typical product concentrations. Real-world results vary with water temperature, circulation, and product brand — always start with a little less than recommended and retest before adding more.
In what order should I add chemicals?
The correct order is: (1) alkalinity, (2) pH, (3) calcium hardness, (4) chlorine/sanitizer, (5) cyanuric acid, (6) salt. Wait a full pump cycle between each step.
My chlorine is fine but the pool is still green. Why?
Algae can survive when CYA is too high ("chlorine lock"), pH is too far out of range, or the free chlorine reading is falsely elevated by combined chlorines. Shock the pool to breakpoint chlorination and test CYA.
How often should I test my pool water?
Test free chlorine and pH at least twice per week. Test total alkalinity and calcium hardness once per month. Test CYA every 2–3 months or whenever water is replaced.