Calculate the Langelier Saturation Index (LSI) for your pool. Determine if your water is corrosive, balanced, or scale-forming based on pH, temperature, calcium hardness, alkalinity, TDS, and CYA.
Enter your pool's pH, water temperature, calcium hardness, total alkalinity, TDS, and CYA to calculate the Langelier Saturation Index. LSI = 0 is ideal; negative values indicate corrosive water, positive values indicate scale-forming water.
The ideal LSI range is -0.3 to +0.3. Corrosive water (LSI < -0.3) attacks plaster, metal, and equipment. Scale-forming water (LSI > +0.3) deposits calcium carbonate on surfaces and equipment.
To raise LSI: increase pH, calcium hardness, or total alkalinity. To lower LSI: decrease pH, calcium hardness, or total alkalinity. CYA correction (Orenda method) reduces effective alkalinity by CYA/3.