What is ordinarily NOT required for a swimming pool operator to test?

In the context of swimming pool operation and maintenance, the testing requirements generally focus on parameters that are vital for ensuring water safety and quality. Among the options provided, the bacterial count per mL of the water is typically not a routine test that operators are required to conduct on a regular basis.

Regular testing often prioritizes factors such as chemical balance, temperature, and pH levels because these directly affect swimmers' safety and comfort as well as the overall quality of the water. Maintaining the correct chemical balance ensures that disinfectants like chlorine are effective, while monitoring temperature can help to ensure a pleasant swimming environment. pH levels are crucial as they impact the effectiveness of disinfectants and can prevent skin and eye irritation for swimmers.

In contrast, while bacterial counts are important for assessing water quality, they are usually not part of standard daily or frequent testing protocols. Instead, bacterial testing may be conducted less frequently or under specific circumstances, such as after a known contamination incident or during health inspections. This approach allows operators to focus on immediate factors that are more routinely critical to health and safety in the pool environment.