Pool, Spa & Water Treatment Chemistry worked example

Combined Chlorine Breakpoint with combined chlorine reading of 1.5 ppm: a worked example

Push combined chlorine reading up to 1.5 ppm and the picture changes. This example computes every intermediate figure at that operating point. Use it to plan breakpoint chlorination after confirming combined chlorine and facility policy.

The inputs for this scenario

  • Combined chlorine reading: 1.5 ppm (raised for this scenario; the documented default is 0.6)
  • Breakpoint multiplier: 10 x (unchanged)
  • Delivery efficiency correction: 1.11 x (unchanged)
  • Chloramine-event safety buffer: 1 x (unchanged)

Working through the calculation

  • Applying the documented formula (Breakpoint demand = combined chlorine x breakpoint multiplier x efficiency correction x safety buffer) to the inputs above produces each figure below.
  • At this operating point the engine returns 16.65 ppm FC for breakpoint chlorine demand, the number this scenario is built around.
  • At this operating point the engine returns 16.65 value for base product.
  • At this operating point the engine returns 1 x for multiplier.
  • At this operating point the engine returns 15 value for factor a x b.

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 150% above the baseline at 16.65 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. 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

  • Breakpoint chlorine demand: 16.65 ppm FC (headline result)
  • Base product: 16.65 value
  • Multiplier: 1 x
  • Factor A x B: 15 value

Run it with your numbers

  • Every input above is editable in the live Combined Chlorine Breakpoint calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.