The sensitivity of particle counters, relative to conventional turbidimeters, is shown to follow an inverse power relationship with turbidity. It is argued that particle counters are best used as fine-tuning instruments below 0.1 NTU turbidity.
A sample's particle size distribution is also shown to influence monitor sensitivity. The model provided can be used to assess the value of using particle counters at a treatment works. It can also be used to compare the sensitivity of different particle monitors as well as anomalous particle monitor readings.