Professional Water Saturation
Pool LSI (Langelier Saturation Index) Calculator
Calculate your pool’s LSI score to ensure water is neither corrosive (etching plaster & pipes) nor scale-forming (depositing white calcium crusts).
LSI Saturation Factors
Enter water parameters to compute LSI balance
7.6 pH
80°F
LSI Saturation ScoreCorrosive / Aggressive Water
Computed LSI Score
-0.86
(Target: -0.30 to +0.30)
Water is hungry for calcium and will dissolve pool plaster, grout, and copper heating elements.
Professional Water Test Kit
Use Taylor K-2006 Complete Drop Test Kit for precise Calcium & Alkalinity readings.
Check Taylor K-2006 on AmazonLSI Saturation Scale Target
Ideal Range: -0.30 to +0.30 (0.00 is perfectly balanced water).
LSI = pH + TF (Temp Factor) + CF (Calcium Factor) + AF (Alkalinity Factor) − TDS FactorRelated Water Balance Tools
Frequently Asked Questions About Pool LSI
Deep dive into LSI saturation, water aggressiveness, and plaster protection.
The Langelier Saturation Index (LSI) is a calculated formula that measures water's saturation level with calcium carbonate. An LSI score between -0.3 and +0.3 indicates perfectly balanced, neutral water.
A negative LSI (<-0.3) means water is corrosive. Corrosive water actively dissolves calcium from pool plaster (causing pitting and roughness), etches grout, and corrodes copper heat exchangers.
A positive LSI (>+0.3) means water is oversaturated with calcium (scale-forming). It forms white calcium scale crusts on pool walls, clouds water, and clogs pool pump impellers and filter grids.
Water temperature and pH have the highest immediate impact on LSI, followed by Cyanuric Acid (CYA), Total Alkalinity, Calcium Hardness, and Total Dissolved Solids (TDS).