I have the same ozone system (Poseidon) and ORP probe (Apex), and I do notice a difference in ORP levels with ozone. I'm running a very low setting (1.5-2) on the Poseidon for 18 hours/daily - but it still seems to add about 20-25 to ORP (without ozone it typically doesn't go above 325).
I'm not sure about a ORP probe "memory", as it's been quite a bit higher at times (the last 2 months ORP has been peaking between 375-400).

I'm not sure about a ORP probe "memory", as it's been quite a bit higher at times (the last 2 months ORP has been peaking between 375-400).



