Red Sea..Aquazone Plus

[mr_alberta]

Is the Aquazone Plus variable? Regardless, the safest way to do it is with an ORP monitor/controller.

[Pescador]

The Aquazone plus is a monitor controller, the set point can vary + or - 10%.
Not sure what your asking but with the switch at set point you dial the desired ORP level.
Did you do a water change? My ORP can drop a 100 points every time I do a change. Moving or cleaning the probe can cause a big change as well.