1. What is the Langelier Saturation Index?

The Langelier Saturation Index (LSI) is a calculated number used to determine the calcium carbonate stability of water. It indicates whether water is corrosive, scale-forming, or in balance.

2. How Does the Calculator Work?

The calculator uses the LSI formula:

Where:

• \( pH \) — pH value of water
• \( TA \) — Total Alkalinity (ppm)
• \( CH \) — Calcium Hardness (ppm)
• \( TDS \) — Total Dissolved Solids (ppm)
• \( \text{Temp Correction} \) — Temperature adjustment factor

Interpretation:

• LSI > 0: Water is scale-forming
• LSI = 0: Water is balanced
• LSI < 0: Water is corrosive

3. Importance of Pool Water Balance

Details: Proper water balance prevents equipment damage, maintains water clarity, ensures swimmer comfort, and optimizes chemical effectiveness.

4. Using the Calculator

Tips: Enter accurate water test results for pH, total alkalinity, calcium hardness, TDS, and water temperature. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the ideal LSI range for pool water?
A: The ideal range is between -0.3 and +0.3 for balanced water.

Q2: How often should I test my pool water?
A: Test at least weekly during swimming season, and after heavy use or rainfall.

Q3: What causes negative LSI values?
A: Low pH, low alkalinity, low calcium hardness, or low temperature can cause negative LSI values.

Q4: How do I correct high LSI values?
A: Lower pH, reduce alkalinity, or use sequestering agents to prevent scale formation.

Q5: Is LSI applicable to all pool types?
A: Yes, LSI is relevant for all pool types including concrete, fiberglass, and vinyl liner pools.