Calculators AquaChek’s easy to use calculators take the guesswork out of balancing your pool or spa. WaterBalance Calculate how much of each chemical is needed to keep your water in balance. VolumeCalculator Determine the approximate pool volume. Langelier Saturation Index (LSI) Assess the overall balance of the water by entering water test results for pH, temperature, alkalinity, cyanuric Acid, calcium hardness and TDS (Total Dissolved Solids. Gallon / Liters Conversions Convert gallons to liters and vice versa.