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Calcimator

Pool Chemical Balance Calculator

Calculate the Langelier Saturation Index (LSI) to determine if your pool water is corrosive, balanced, or scale-forming.

Inputs

°F
ppm
ppm
ppm

Results

Langelier Index (LSI)

1.34

Water Condition

2

Adjustment Magnitude1.34
Target pH6.06
Target Alkalinity73 ppm
How to Use This Calculator
  1. Enter current pH, water temperature, calcium hardness, total alkalinity, and TDS readings.
  2. Review the Langelier Saturation Index and recommended chemical adjustments.
  3. Retest after adjustments — pool chemistry affects each parameter interactively.

How the result changes with pH Level

pH LevelLangelier Index (LSI)Water Condition
6.30.241
7.050.992
7.951.892
8.72.642

What each input means

pH Level
Current pool water pH reading (ideal: 7.2-7.6).
Water Temperature
Pool water temperature in Fahrenheit.
Calcium Hardness
Calcium hardness reading (ideal: 200-400 ppm).
Total Alkalinity
Total alkalinity reading (ideal: 80-120 ppm).
Total Dissolved Solids
TDS level (fresh fill ~300, typical pool 1000-2000 ppm).

What each result means

Langelier Index (LSI)
LSI value. Negative = corrosive, 0 = balanced, Positive = scale-forming.
Water Condition
0 = Corrosive, 1 = Balanced, 2 = Scale-forming.
Adjustment Magnitude
How far the LSI is from ideal balance (0).
Target pH
pH level that would bring LSI to 0 with current conditions.
Target Alkalinity
Suggested alkalinity adjustment to help balance water.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    pH Level = 7.4, Water Temperature = 82, Calcium Hardness = 250, Total Alkalinity = 100 = 5 input(s) provided
  2. Calculate Langelier Index
    Langelier Index
    1.34 = 1.34
  3. Calculate Water Condition
    2 = 2
  4. Calculate Adjustment Magnitude
    Adjustment Magnitude
    1.34 = 1.34
  5. Calculate Target pH
    Target pH
    6.06 = 6.06

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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