Final answer:
A manual conductivity reading should not be completed when the machine is in bypass mode because it can lead to inaccurate readings.
Step-by-step explanation:
A manual conductivity reading should not be completed when the machine is in bypass mode because bypass mode allows the flow of electricity in a different path, which can produce inaccurate readings. Conductivity measurements are used to determine the ability of a solution to conduct electricity, and the machine needs to be properly calibrated and in its standard operating mode to obtain reliable results.