Swimming Pool Water Balance Equations Formulas Calculator
Maintenance Hot Tub Pool Wading

Below are two methods to solve for the Langelier Saturation Index. Method 1 automatically calculates the various factors (temperature, hardness and alkalinity). For method 2, the user will need to manually look up the values from the table and place the values into the calculator.

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Water Temperature (°F)	Temperature Factor (TF)	CaCO3 PPM	Calcium Hardness (CF)	Total Alkalinity PPM CaCO3	Alkalinity Factor (AF)
32	0.0	5	0.3	2	0.7
37	0.1	25	1.0	25	1.4
46	0.2	50	1.3	50	1.7
53	0.3	75	1.5	75	1.9
60	0.4	100	1.6	100	2.0
66	0.5	150	1.8	150	2.2
76	0.6	200	1.9	200	2.3
84	0.7	300	2.1	300	2.5
94	0.8	400	2.1	400	2.6
105	0.9	800	2.5	800	2.9
128	1.0	1000	2.6	1000	3.0

Langelier Saturation Index (SI)	Condition
-0.5 < SI <0.5	balanced
> 0.5	scale forming over saturated
< 0.5	corrosive under saturated

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Inputs:

pH
temperature factor (TF)
calcium hardness factor (CF)
alkalinity factor (AF)

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Conversions:

pH	=	0		=	0
temperature factor (TF)	=	0		=	0
calcium hardness factor (CF)	=	0		=	0
alkalinity factor (AF)	=	0		=	0

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Solution:

Langelier Saturation Index (SI)

=

HAS NOT BEEN CALCULATED

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References - Books:

Haan, William D. and Johanningsmeier, Julie S. Swimming Pool Pest Management: A Training Manual for Commercial Pesticide Applicators and Swimming Pool Operators. Kent County Health Department and Michigan State University. Unknown date.

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