If a pool has a pH of 7.3, a temperature of 67°F, calcium hardness of 250, total alkalinity of 100, and TDS of 1500, what is the Saturation Index Value?

To determine the Saturation Index (SI) Value, you can use the formula:

SI = pH + TF + CH + TA - 12.1

Where:

• pH is the measured pH of the water.

• TF (temperature factor) is based on the water temperature (for 67°F, TF is approximately +0.2).

• CH is the calcium hardness expressed in parts per million (ppm) divided by 10.

• TA is total alkalinity expressed in ppm divided by 10.

Now, let’s plug in the values:

1. pH = 7.3

2. TF for 67°F = +0.2

3. Calcium hardness (CH) = 250 / 10 = 25

4. Total alkalinity (TA) = 100 / 10 = 10

Now substituting these into the formula gives:

SI = 7.3 + 0.2 + 25 + 10 - 12.1

Calculating this step-by-step:

• 7.3 + 0.2 = 7.5

• 7.5 + 25 = 32.5

• 32.5 +