A frequently made mistake in the use of automatic controllers takes place on the commercial side.

When it comes to commercial pools and spas, health codes often dictate that automated controllers be calibrated with a test kit to make sure the unit is correctly monitoring the chemistry levels. But it’s easy for conscientious operators to become overzealous.

“You might have three people in a day looking at a chemical controller and calibrating it to a test-kit reading,” says Ron Akin, vice president of sales at Santa Barbara Control Systems in Santa Barbara, Calif. “The problem with that is at different times of the day and with different people looking at the same test results, you’re going to see different things.”

These conflicting readings may cause multiple users to constantly adjust the controllers, even when there may not be anything wrong.

“The tendency to overcalibrate the unit can be a problem because people are overriding what the sensor itself is saying,” Akin says. “Although it should be checked, if it’s within the margin of error of the accuracy of the probe, we really don’t recommend overcalibrating the controller.”

Akin recommends that calibration occur at the same time each day, so that usage and lighting conditions are more consistent, and the results will look as similar as possible. It’s also best if the fewest people possible calibrate it, to minimize conflicting translations of the results.

“As long as you’re within the health department’s accepted realm of what your low and what your high is, and if you’re around your set point, you really should kind of let the controller operate with as little interference as possible,” he says.

If the unit must be calibrated more often than normal and a cause can’t be found, it is best to call the manufacturer. There may be a problem with the sensor or controller.