Langelier Saturation Index (LSI)

Estimates whether calcium carbonate will tend to dissolve or precipitate by comparing actual water pH to the pH at calcium carbonate equilibrium. Negative values favor dissolution, zero is equilibrium, positive values favor precipitation.

$$\text{LSI}=\text{pH}-{\text{pH}}_s$$

Variables

Symbol	Meaning	Unit
$\text{pH}$	Measured pH of the water	unitless
${\text{pH}}_s$	Theoretical pH at calcium carbonate saturation (equilibrium)	unitless

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Part of The Blueprint of Water