Water balance calculator

LSI water balance

PHTA-style saturation-index calculation with CYA-corrected alkalinity and revised TDS factors.

A pool water sample and testing kit beside clear blue pool and spa water

Measured inputs

Calculate saturation balance

Use fresh test results and confirm every product value against its label.

pHWater temperature (°F)Calcium hardness (ppm)Total alkalinity (ppm)Cyanuric acid (ppm)Total dissolved solids (ppm)

Langelier Saturation Index

-0.04

Within the PHTA balance range (−0.3 to +0.5)

Balance is not sanitationLSI does not say whether water is disinfected or safe to use. Check sanitizer, pH, clarity, temperature, and physical safety separately.

Corrected carbonate alkalinity: 90.4 ppm after the pH-specific CYA correction
Factors: CF 2.077 + AF 1.956 + TF 0.625 − 12.2
Source: PHTA Water Balance Indexes and methodology

How to use this result

A planning quantity, not an instruction to pour.

1. Verify

Recheck volume, test reading, product strength, density or purity, and the selected target.

2. Read the label

Use the label’s application method, protective equipment, maximum dose, spacing, and re-entry directions.

3. Add separately

Never combine chemicals. Add one product at a time with circulation as directed.

4. Retest

Start with the staged amount, allow the label-directed circulation time, and measure again.