Pool, Spa & Water Treatment Chemistry worked example
LSI Water Balance with measured water ph of 19 pH: a worked example
Push measured water ph up to 19 pH and the picture changes. This example computes every intermediate figure at that operating point. Use it to screen scale or corrosion risk before deeper LSI review.
The inputs for this scenario
- Measured water pH: 19 pH (raised for this scenario; the documented default is 7.5)
- Total alkalinity factor: 2 index (unchanged)
- Calcium hardness and temperature factor: 2.6 index (unchanged)
- Saturation constant: -12.1 index (unchanged)
Working through the calculation
- Applying the documented formula (Simplified LSI = pH + alkalinity factor + calcium and temperature factor + saturation baseline (negative)) to the inputs above produces each figure below.
- At this operating point the engine returns 23.6 index for simplified lsi, the number this scenario is built around.
- At this operating point the engine returns 19 index for element 1.
- At this operating point the engine returns 2 index for element 2.
- At this operating point the engine returns 2.6 index for element 3 + 4.
How this compares with the baseline
- Against the tool's baseline example, where measured water ph sits at 7.5 pH and the headline result is 12.1 index, this scenario comes in 95.04% above the baseline at 23.6 index.
- It computes a simplified Langelier Saturation Index by summing pH and the alkalinity, calcium, and temperature factors and subtracting a saturation constant. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.
Results at a glance
- Simplified LSI: 23.6 index (headline result)
- Element 1: 19 index
- Element 2: 2 index
- Element 3 + 4: 2.6 index
Run it with your numbers
- Every input above is editable in the live LSI Water Balance calculator, which recalculates instantly and can be shared with the inputs intact.
Last reviewed 2026-05-12.