ORP Scaring Me

[TheReefGeek]

Where is your ORP probe located? Only thing I can think of is that your ozonizer is pumping in ozone into your tank, but the ORP is "spread around" the rest of your tank until quite a while, so by the time your ORP probe detects the increased ORP, the area your ozone is getting injected into is much higher than your desired level, and when this "spreads out" to your probe, you have a much higher ORP than desired when the unit kicks out.

If this makes any sense, then you could try relocating your ORP probe closer to the output of your canister filter lets say, and you might not get as big of swings.

Also, if you know someone else with an ORP meter, borrow their unit to verify the readings against yours, maybe your controller/probe is wonky.