Pool, Spa & Water Treatment Chemistry worked example

Oxidizer Demand with estimated contaminant load of 25 bather-hours or units: a worked example

This worked example runs the oxidizer demand numbers for a tougher week than the baseline: estimated contaminant load of 25 bather-hours or units instead of the typical 50 bather-hours or units. Estimate oxidizer demand from contaminant load, conversion factor, and treatment efficiency.

The inputs for this scenario

  • Estimated contaminant load: 25 bather-hours or units (the input this scenario stresses; the baseline uses 50)
  • Oxidizer demand factor: 0.08 ppm / unit (held at the documented default)
  • Treatment efficiency correction: 1.11 x (held at the documented default)
  • Safety buffer factor: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Oxidizer demand = contaminant load x demand factor x efficiency correction x safety buffer.
  • Oxidizer demand works out to 2.22 ppm at these inputs, and this is the headline figure for the scenario.
  • Base product works out to 2.22 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 2 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where estimated contaminant load sits at 50 bather-hours or units and the headline result is 4.44 ppm, this scenario comes in 50% below the baseline at 2.22 ppm.
  • Use it before shocking after a high-bather-load event, a storm, or an algae or chloramine problem, when you need a defensible dose target instead of a habit dose. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Oxidizer demand: 2.22 ppm (headline result)
  • Base product: 2.22 value
  • Multiplier: 1 x
  • Factor A x B: 2 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Oxidizer Demand calculator, set estimated contaminant load to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.