What should always be done before calibrating pH probes?

Before calibrating pH probes, it is essential to clean the probes. This action is crucial because contaminants, residues, or buildup on the electrode can significantly affect the accuracy of the pH readings. If the probe is not clean, it may provide misleading data, leading to improper adjustments or decisions in wastewater management practices.

Cleaning the probes ensures that they can respond accurately to the pH of the solutions used during calibration. It's a standard procedure in maintaining the integrity and performance of the pH measurement system. By removing any deposits or foreign materials, you enhance the reliability of the calibration process and the subsequent measurements taken in the field.

While checking reagent levels, testing water temperature, and inspecting wiring are all important steps in the maintenance and operation of pH equipment, they do not address immediate influences on the probe's performance right before calibration like cleaning does. Proper cleaning is thus a foundational step to ensure subsequent calibration is accurate and reliable.