High ORP - Redox Potential

[Osama]

My Neptune system on my 180g reef ORP reading is over 420mv. I thought that was good till I got a flyer with water values that identifies any reading above 450 as requiring caution!!and that optimal value should be 250-350mv.
Opinions are appreciated and an explanation of what causes high readings and impact on inhabitants.

 

[wastedincome420]

Wish I could help.
I would also like to know about orp readings. I have a Octopus3000 and would like to know where I should have the set points. I have a Ozone unit too, where should I have it set to come on and go off???