PREPARING THE POOL WATER
8
Saturation Index (SI)
The Saturation Index is a formula used to predict the calcium carbonate saturation of water, that is, whether your water will
precipitate, dissolve, or be in equilibrium with calcium carbonate. Your water is properly balanced if the SI is 0 ± 0.3. If your SI
is greater than 0.3, scaling and staining will occur. If your SI is less than -0.3, then the water is corrosive to metallic fixtures and
aggressive to plaster surfaces and vinyl liners. A high or low SI can cause premature damage to the cell, equipment or pool
finish. As a general rule, higher concentrations of calcium, total dissolved solids, pH, and alkalinity all promote a greater
tendency for scale. Scaling potential also increases with increasing temperature.
Use the chart below to determine your overall water balance. Test your water for pH, water temperature, Calcium Hardness,
Total Alkalinity and Salt Level and use the equivalent Factors (TF, CF, AF, Constant) from the chart below to determine your
Saturation Index. Adjust your chemicals to maintain balanced water.
pH + TF + CF + AF – SC = SI
Temperature
TF
Calcium
Hardness
CF
Total
Alkalinity
AF
Salt Level
SC
60
o
F 15.6
o
C
0.4 150
ppm 1.8
75
ppm 1.9
0 – 1000 ppm
12.1
66
o
F 18.9
o
C
0.5 200
ppm 1.9
100
ppm 2.0
1001 - 2000 ppm
12.2
76
o
F 24.4
o
C
0.6 250
ppm 2.0
125
ppm 2.1
2001 - 3000 ppm
12.3
84
o
F 28.9
o
C
0.7 300
ppm 2.1
150
ppm 2.2
3001 - 4000 ppm
12.4
94
o
F 34.4
o
C
0.8 400
ppm 2.2
200
ppm 2.3
4001 - 5000 ppm
12.5
103
o
F 39.4
o
C
0.9 600
ppm 2.4
250
ppm 2.4
5001 - 6000 ppm
12.6
-.3 -.2 -.1 0 .1 .2 .3
Corrosive to
metals, etches
plaster
finishes, and
irritates skin
OK
Scaling,
staining, and
cloudy water
conditions
Examples
Water test results #1:
Total Alkalinity = 125 ppm
=> AF = 2.1
Calcium Hardness = 400 ppm
=> CF = 2.2
pH = 7.4
=> pH = 7.4
Water Temperature = 84 F
=> TF = 0.7
Salt Level = 3000 ppm
=> SC = 12.4
7.4 + 0.7 + 2.2 + 2.1 – 12.4 = 0 (Water is perfectly balanced)
Water test results #2:
Total Alkalinity = 200 ppm
=> AF = 2.3
Calcium Hardness = 600 ppm
=> CF = 2.4
pH = 7.8
=> pH = 7.8
Water Temperature = 84 F
=> TF = 0.7
Salt Level = 3000 ppm
=> SC = 12.4
7.8 + 0.7 + 2.4 + 2.3 – 12.4 = 0.8 (Water is scale forming)
Содержание Pool Pilot 75003
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