Orp?

[Griffer]

Can someone define why ORP is important? Or laugh me off of the forum? I searched and found nothing here. I googled it and read some info that was about as inconclusive as I have ever seen on any subject.

Anyway, I have installed a new Apex controller and, among other things, it monitors ORP. About the only thing I can tell is the ORP reading is always inverse to the pH reading. It always ranges from about 315 to 380mv.

So, what is it telling me about my tank's health??

Thanks for any help!

Gene

[uhuru]

I'm not sure how conclusive any info you get is going to be, since ORP itself is not conclusive. Here's more than you probably wanted to know:

http://reefkeeping.com/issues/2003-12/rhf/feature/index.php

[Randy Holmes-Farley]

IMO, that ORP is fine. The article has more. :)

[Griffer]

Thanks for the replies. I take it, then, that it's not a concern unless one day it suddenly changes significantly from what, for my tank, is normal? Then I suppose it's telling me that it's time to check parameters?

Gene

[Randy Holmes-Farley]

Not water parameters per se, but maybe for dead organisms.

I discuss that in the above article, including this summary:

Recommendations for ORP

ORP is an interesting, if complicated, measure of the properties of water in a marine aquarium. It has uses in monitoring certain events in aquaria that impact ORP but may be otherwise hard to detect. These events could include immediate deaths of organisms, as well as long term increases in the levels of organic materials. Aquarists that are monitoring ORP in an aquarium, and are doing things that otherwise seem appropriate for maintaining an aquarium (such as increasing aeration, skimming, use of carbon, etc.) may find monitoring ORP to be a useful way to see progress.

ORP measurements are very susceptible to errors. Aquarists are strongly cautioned to not overemphasize absolute ORP readings, especially if they have not recently calibrated their ORP probe. Rather, the most useful ways of using ORP involve looking at changes in measured ORP.

Some aquarists use oxidizers to raise ORP. Those additions may be of benefit in some aquaria, and they may be beneficial in ways that aren't demonstrated by changes in ORP alone. I've never added such materials to my aquarium. In the absence of convincing data otherwise, such additions seem to me to have more potential risk than is justified by the demonstrated and hypothesized benefits.