Weird ORP

[Wes888]

I thought ORP more or less has a tiny little bit related to oxygen level. The ORP for my new 125g tank, after running it for a week, empty with just sand and a little LR, with lights on regular schedule, was just about 120!!!! That's when I first got my ORP probe a week ago.

I've been watching it everyday and it constantly increases about 120 EVERYDAY! Constantly! And today, it gets to 390 an hour ago. I'm sure it'll either stays around 400 or get lower since I added all live stock to the tank yesterday.

The thing that interest me is that what the ORP might have been before I got the probe 2 weeks ago! Why it was so low?

This is now:

 

[bjohanson1234]

I didnt know what ORP stood for. So I looked it up and found this site.

ORP and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

Heres a little excerpt

"It turns out that oxygen molecules (O2) can occasionally morph into some of these better fighters (such as hydrogen peroxide), sometimes all on their own, but most frequently when they get blasted with UV light."

So from my understanding, the O2 can get changed into other, more ORP, type of molecules with UV light.

If I recall, you have MH lighting which puts out quite a bit of UV light even with the UV shields that they put on them. Since there is nothing really in your tank for these ORP's to react with, they will increase.

This is just my understanding of this article I found but hope it helps.

Brian

 

[Wes888]

ah, that make sense! I do have a 55W UV sterilizer on all the time. I think that's where the ORP came from!

 

[bjohanson1234]

Could be. Once you get some life in there, I am sure that it will come down

 

[ccCapt]

Something doesn't look right. Are you injecting ozone? Did you calibrate the probe?

 

[Wes888]

no ozone connected. I didn't calibrate this probe that's connecting to the Apex controller. I have a calibrated Pinpoint that was using in the old tank. I just moved it over and it's reading 335 while the apex one is reading 398.

It doesn't concern me too much since like most article mentioned, it's not the exact number that's important. It is the change of the ORP that needs to be looked at.

After putting live stock into the tank for 1 day, the chart looks a lot more normal now.