ORP

I know there is not much knowledge out there on ORP.....but I figured I would ask around here and over in the chem forum at RC.....
If you measure ORP, what are your average readings? Do you see it go up and down in relation to feedings, cleanings, water changes, light cycles, temperature?
I have no idea what makes mine go up or down, or even if my ORP probe is reading the right readings. It has been online now for about a month.
Finally, I am ALWAYS in the 400-440 range. This totally pisses me off because I have an awesome new ozone setup ready to go but I am afraid it will blast my ORP readings through the roof (over 450), rendering my setup useless since I have my apex set to shut down the ozone if my ORP reads over 400.
So to summarize:
What are your average ORP readings?What causes your ORP to fluctuate?

 

Last night I cleaned my ORP probe for the first time (been in tank 2 months). Now the ORP is down to 'normal' levels....about 250-300mv

Also, my salinity probe caught a small air bubble and was keeping a stable salinity of 31 after a water change. My first reaction was to add salt. But I have learned to ALWAYS QUESTION MY FIRST REACTION in this hobby. ALWAYS. So instead I cleaned all my probes. And my problem(s) are fixed!