Saturation Index Calculator

You can use the form to the right to calculate your saturation index.

To determine whether your pool water is balanced we will use the Saturation Index. First complete and record water testing of the pH, calcium hardness, alkalinity, temperature, and total dissolved solids. Then using the chart below, take the factors and add them together. Subtract that number from the constant of 12.1. Balanced water will have an index between -0.5 and +0.5. Over +0.5 is scale forming, below -0.5 is corrosive.

EXAMPLE
Test Results Using factors

pH = 7.5  7.5
Temp. = 85  0.7
TA = 100  2.0
CH = 200  1.9 
 12.1
constant factor= -12.1
  0 = perfectly balanced water, no correction needed
pH level =
Temperature =
Total Alkalinity =
Calcium Hardness =
- 12.1 =

The purpose of balancing pool water is to prevent corrosion or scaling. These conditions have adverse effects on the pool equipment, the pool surface, and can cause cloudy water.

IMPORTANT: The suggested range (measurement in ppm) for these parameters is vitally important. Even if the Saturation Index is reached and the suggested ranges are not met, you will experience difficulties.

Suggested ranges: pH 7.2 to 7.6
Alkalinity 80 to 120 ppm
Calcium 200 - 300 ppm (200 minimum)

SATURATION INDEX CHART

Temp TFactor Calcium CFacter Alkalintiy AFactor
76 0.6 100 1.6 50 1.7
84 0.7 150 1.8 75 1.9
94 0.8 200 1.9 100 2.0
105 0.9 300 2.1 150 2.2
400 2.2 200 2.3
800 2.5 300 2.5
1,000 2.6 400 2.6

Balanced water will have an index between -0.5 and +0.5.
Over +0.5 is scale forming, below -0.5 is corrosive.

Need to adjust chemicals? Click here to calculate how much to add.