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CSI Calculator

The CSI Calculator lets you test the Calcite Saturation Index for any body of water on the spot — without adding it to your pools list. It supports pools, spas, and fountains, making it useful when you need a one-time reading for any body of water you're not actively managing in FlowBeacon.

Desktop view

What Is the CSI?​

The Calcite Saturation Index (CSI) measures how balanced your water is with respect to calcium carbonate. A balanced CSI means the water is neither scaling nor corrosive, which protects your pool surfaces and equipment.

  • Negative CSI — Water is aggressive and may corrode surfaces or equipment
  • Near zero — Water is balanced
  • Positive CSI — Water is scale-forming and may leave calcium deposits

Inputs​

  • pH — Current pH reading
  • Temperature — Water temperature in °F
  • Calcium Hardness — Calcium hardness level in ppm
  • Total Alkalinity — Total alkalinity in ppm
  • Cyanuric Acid (CYA) — Stabilizer level in ppm
  • Free Chlorine — Free chlorine level in ppm
  • Salt / TDS — Salt or total dissolved solids level in ppm
  • Borates (optional) — Borate level in ppm

When to Use This Calculator​

This calculator is ideal for service professionals testing a body of water for the first time, or for any situation where you want a quick CSI check without creating a full profile in FlowBeacon. It works for pools, spas, and fountains.