What does ORP measurement mean in practice?
The ORP electrode measures the potential relative to a reference electrode, and the result responds to all redox pairs present, not to a single oxidant.
When does it matter?
Values from different pH, temperatures and electrode types should not be directly compared as a measure of disinfection.
Which solutions are related to it?
The electrode is kept clean, checked with a control solution and the ORP is interpreted together with the pH and disinfectant concentration.