apex ORP

n00b · Jun 6, 2012

so i added an ORP probe today.. i enabled it.. and it is staying around 249-252.. is this correct? is this low?

thewackyreefer · Jun 6, 2012

Here's a great article: ORP and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

n00b · Jun 7, 2012

read it.. now my ORP is at 218.. been on a downslope since last night.

n00b · Jun 7, 2012

so what does the ORP "need" to be? and what can be done to raise or lower?

JSB · Jun 7, 2012

First off, it needs to be calibrated. Secondly, the number is generally used as a reference for trending water quality. A single reading is not of much value (at least to me). My ORP drops 50 points every time I feed and recovers over the next 12-24 hours.. I have seen tanks that hover around 400+. Mine stays a little shy of that around 360. If you see upward trends, water quality is improving, down is decreasing. If something dies in the tank, you will likely see significant decline in the short term. Not sure if this helps, but that is how I use it.

n00b · Jun 7, 2012

whats the best way to calibrate it? and mine is at 214 right now. my halides are about to come on also..

JSB · Jun 7, 2012

You need some 400mv Reference solution. The procedure is in the manual.

n00b · Jun 7, 2012

from the manual:

ORP Calibration

It is not necessary to calibrate the ORP probe of the AquaController Apex.

where do i get such solution..

JSB · Jun 7, 2012

BRS and Premium Aquatics sells what you need. Read this http://www.neptunesys.com/PM1-20104031_WEB.pdf and it explains how to calibrate it with 4.0 and 7.0 solutions. It also tells you that you initial readings will be low until it breaks in. I was almost certain that there was a 400mv way to calibrate it, but it has been a while. Now, when looking over some stuff, I see the two step (4.0, 7.0) method is the way neptune does their ORP calibration.