Using The Saturation Index; Salt Addition Chart - Aquacal Pool Pilot Digital Nano Owner's Manual

10.2 USING THE SATURATION INDEX

This index is used by pool professionals to ensure that your total water chemistry does not fall into a
corrosive or scaling condition. Either condition can cause premature damage to the cell, any of your
other equipment, as well as your cementitious finish.
The Saturation Index is composed of the following factors:

pH as tested

Plus the Temperature factor

Plus the Calcium Hardness factor

Plus the Alkalinity factor

Minus the Total Dissolved Solids factor (in this case the bulk of the dissolved solids are salt)
This is expressed in the formula SI = pH + TF + CF + AF – TDSF and uses the following charts:
TEMPERATURE TF
60 F 15.6 C 0.4
66 F 18.9 C 0.5
76 F 24.4 C 0.6
84 F 28.9 C 0.7
94 F 34.4 C 0.8
103 F 39.4 C 0.9
Example:
WATER TEST RESULTS
pH = 7.8
Temperature is 84°F
Calcium Hardness is 600 ppm (mg/L)
Total Alkalinity is 200 ppm (mg/L)
Salt is 3500 ppm (mg/L)
Corrosive to metals,
etches plaster
finishes, and irritates
skin.
If adjustments need to be made to balance the water, the recommended sequence is as follows:
1) Test and adjust Total Alkalinity. This may reduce pH so wait at least 8 hours before proceeding.
2) Test again and adjust pH, then
3) Adjust Calcium Hardness.

10.3 SALT ADDITION CHART

The following salt charts are included for reference only; once programmed to the correct water volume,
the controller will automatically indicate how much salt is required to achieve optimum water salinity.
The salt in the pool is constantly recycled during normal operation. Loss of salt during a swimming
season should be minimal. Filter backwashing, draining due to rain water overflow, splashing, bathing
suit drag out, and leaks are typical ways salt is lost. Salt does not leave the pool when water
evaporates.
1) Determine pool/spa volume in (Gallons or Liters).
2) Find current salt level in the pool. Many pools will already have a significant salt residual, so
always test water before adding salt (This can be obtained from the Control display or by testing
water.)
CALCIUM
CF
HARDNESS
150 ppm (mg/L) 1.8
200 ppm (mg/L) 1.9
250 ppm (mg/L) 2.0
300 ppm (mg/L) 2.1
400 ppm (mg/L) 2.2
600 ppm (mg/L) 2.4
FACTORS
pH = 7.8
TF = 0.7
CF = 2.4
AF = 2.3
TDSF = 12.4
-0.3 -0.2 -0.1 0
OK
TOTAL
AF
ALKALINITY
075 ppm (mg/L) 1.9
100 ppm (mg/L) 2.0
125 ppm (mg/L) 2.1
150 ppm (mg/L) 2.2
200 ppm (mg/L) 2.3
250 ppm (mg/L) 2.4
SI = 0.8
Water is scale forming and needs to
be balanced
0.1 0.2 0.3
Page 39
SALT LEVEL
0000 - 1000 ppm (mg/L)
1001 - 2000 ppm (mg/L)
2001 - 3000 ppm (mg/L)
3001 - 4000 ppm (mg/L)
4001 - 5000 ppm (mg/L)
5001 - 6000 ppm (mg/L)
WATER SATURATION
Scaling, staining, and
cloudy water conditions.
TDSF
12.1
12.2
12.3
12.4
12.5
12.6
Table 8