ORP Readings - How High is too High?

[aquareefer]

Three weeks ago I did a major cleaning job of my 375 gallon reef system. Everything is doing great (fishes, reef, soft corals, LPS's, SPS's etc.) but I do have a question about my ORP reading(s). Before cleaning, my ORP average was about 425, with very occasional dips to about 350 or a little lower. I have always been a fanatic when it comes to clean water, but now my ORP reading is 450 on a regular basis (absolutely highest reading has been 454).

It's my understanding that, simply speaking, the bacterial action in the marine water virtually ceases when the ORP is this high.

Am I right on this, and is there cause to be concerned? What's your take on this? Thanks!

aquareefer
Tage Blytmann

 

[dnjan]

How recent is your probe calibration?

 

[aquareefer]

Hi Don, thanks for your interest.
I am using an American Marine Pinpoint ORP controller installed about a year ago. At the time the probe was carefully calibrated according to manufacturer's instructions. After the calibration, the ORP settled at 425 (+- a few points) and (except for occasional dips) has been very steady ever since. My system is about three and a half years old, always with excellent water quality. I have assumed everything to be ok, calibration-wise, since the "default" reading over the last year had been so steady. Then, after my major cleaning endeavor, the ORP went to about 450, and I started to question things.

Tage

 

[dnjan]

First thing I would do is clean and calibrate your probe. The tank cleaning might have resulted in some "gunk" getting in the probe.