ORP controller question

[christyf5]

Ok this might be a silly question but I just can't wrap my head around this.

I have a Sander ozonizer 0-50mg/hr hooked up to an airdryer and a Milwaukee SMS510 ORP monitor/controller. The controller is set so that an alarm (flashing light) goes off when the ORP goes below its set point. I'm not quite sure what the "alarm" is supposed to do ro me because I'm assuming that at that point the ozonizer turns on and gets the ORP back up to where you have the controller set at. I guess the flashing light makes things more exciting

I have my controller set at 400. The monitor usually reads about 450 or so, I clean the probe weekly to make sure its working properly. However, the only time I see the light on on the ozonizer (ie. its turned on) is when I do a water change and the ORP goes down to about 350 or so. So my question is, if I have the controller set at 400 and the ozonizer never kicks in unless the ORP is below 400. How the heck am I getting an ORP reading of 450?

[Pescador]

Hey Christy
I don't have the Milwaukee controller I have the Red Sea but it sounds like the same idea. Have you checked it with calibration fluid?
Some tanks run a high ORP without ozone but 450 sounds high. My controller has a set point accuracy of + -10% so it can drift up to 40Mv at 400Mv. Also readings can be different in different parts of your tank or sump so maybe try moving the probe around.
Everyone's tank is different but mine stays between 325-375 with 200mg running steady. It drops to about 225 after a water change.
Also on my Red Sea you can't set the ozone level unless the unit is producing ozone.(the red light is on)

[vanreefer]

sounds like it is working the way it is supposed to ie the ozone generator is only given power when theORP level is below the set point, BUT I agree that you probably need to calibrate the probe as an ORP of 450 without ozone seem improbable... at least in my tank anyway