Pool, Spa & Water Treatment Chemistry worked example

Combined Chlorine Breakpoint with combined chlorine reading of 0.3 ppm: a worked example

Suppose combined chlorine reading falls to 0.3 ppm. This page works the full calculation at that level so you can see exactly which result moves and by how much. Estimate breakpoint oxidation demand from combined chlorine, a breakpoint multiplier, and delivery efficiency.

The inputs for this scenario

  • Combined chlorine reading: 0.3 ppm (the input this scenario stresses; the baseline uses 0.6)
  • Breakpoint multiplier: 10 x (held at the documented default)
  • Delivery efficiency correction: 1.11 x (held at the documented default)
  • Chloramine-event safety buffer: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Breakpoint demand = combined chlorine x breakpoint multiplier x efficiency correction x safety buffer.
  • Breakpoint chlorine demand works out to 3.33 ppm FC at these inputs, and this is the headline figure for the scenario.
  • Base product works out to 3.33 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 3 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where combined chlorine reading sits at 0.6 ppm and the headline result is 6.66 ppm FC, this scenario comes in 50% below the baseline at 3.33 ppm FC.
  • It computes the breakpoint free-chlorine demand in ppm by multiplying the combined chlorine reading by the breakpoint factor, a delivery-efficiency correction, and a safety buffer. When the numbers land here, the stressed input is the lever to work; the walkthrough above shows exactly how much each output recovers as it climbs back toward the baseline.

Results at a glance

  • Breakpoint chlorine demand: 3.33 ppm FC (headline result)
  • Base product: 3.33 value
  • Multiplier: 1 x
  • Factor A x B: 3 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Combined Chlorine Breakpoint calculator, set combined chlorine reading to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.