Saturation index
The saturation index (Si) relates to the calcium and alkalinity in the water and is an indicator of the pool water "balance". Your water is properly balanced if the Si is 0 ±.2. If the Si is below
Si = pH + Ti + Ci + Ai - 12.1
∫C
12
16
19
24
29
34
39
∫F
53
60
66
76
84
94
103
Ti
.3
.4
.5
.6
.7
.8
.9
Calcuim
Hardness
75
100
125
150
200
250
300
400
600
800
Ci
1.5
1.6
1.7
1.8
1.9
2.0
2.1
2.2
2.4
2.5
Total
Alkalinity
75
100
125
150
200
250
300
400
600
800
Ai
1.9
2.0
2.1
2.2
2.3
2.4
2.5
2.6
2.8
2.9
How to use: Measure pool pH, temperature, calcium hardness, and total alkalinity. Use the chart above to determine Ti, Ci,and Ai from your measurements. Insert values of pH, Ti, Ci and Ai into the above equation. If Si equals .2 or more, scaling and staining may occur. If Si equals
CORROSIVE 
SCALING
OK
2