How important is orp really?

MACHO · Mar 3, 2023

got a 200 gallon tank with refugium skimmer and filter roller also biopellet reactor. Orp dropped to 244 stays around 250 just did a water changed and didn’t move any at all. How are y’all judging when orp becomes a problem. Have a lost fish that idk where he went but I suspect that this might be the cause but still orp has always been low.

Randy Holmes-Farley · Mar 4, 2023

I do not consider absolute ORP values to be particularly useful, except that when using very high ORP materials such as ozone, you do not want it to get too high.

Kpdiver · Mar 17, 2023

Randy Holmes-Farley said:
I do not consider absolute ORP values to be particularly useful, except that when using very high ORP materials such as ozone, you do not want it to get too high.

How high is too high? What is the target number we should be looking at? I run a Poseidon 200 on my 280gal display directly into my skimmer. I have it connected to the same outlet as my skimmer on the Apex so when the skimmer is off, so is the poseidon. I've been keeping my orp around 345.

Randy Holmes-Farley · Mar 17, 2023

Kpdiver said:
How high is too high? What is the target number we should be looking at? I run a Poseidon 200 on my 280gal display directly into my skimmer. I have it connected to the same outlet as my skimmer on the Apex so when the skimmer is off, so is the poseidon. I've been keeping my orp around 345.

ORP and the Reef Aquarium - Reefkeeping.com

I’d try to keep it below 450 mV.