PH relation to ORP

[ArisReef]

Hi,

I am running a NEPTUNE SYSTEMS Aqua Controller III, having a Temp. probe, PH probe and an ORP probe.

In the controller's menu/ set up mode for the ORP I have the option to set ON/OFF the PH comparison.

The same happens in the PH set up mode where I have the option to set the Temperature comparison ON/OFF.

Of course I understand the relation of the PH value with the temperature, but what about the ORP comparison with PH?

Thank you :)

[Billybeau1]

[welcome]

As pH drops, ORP rises. As pH rises, ORP drops.

[Craig Lambert]

ArisReef,

Welcome. You might try posting this question on the Chemistry forum located here: http://reefcentral.com/forums/forumdisplay.php?s=&forumid=112
I'm sure Randy can answer that for you.

[Billybeau1]

Well I'm not sure what was wrong with my answer but here is a paragraph from Randy's article about ORP in the Reef Aquarium

"What about pH? pH can impact the ORP readings in aquaria. Often, ORP goes down as pH rises. A typical aquarium ORP reading will change on the order of 59 mv/pH unit. The easiest way to understand this is to simply think of pH as a measure of hydrogen ions (H+) in solution, and to think of H+ as being on the side of the oxidizers. In reality, H+ doesn't usually oxidize things itself (though it can), but more typically it can hype up other oxidizers, like oxygen, making them much more potent. So during the course of a 24-hour day in a reef aquarium, ORP will vary as pH and O2 also vary."

Here is the rest of the article

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

[Craig Lambert]

Billybeau1....In all honesty, I didn't see your answer. I noticed the big "Welcome" but overlooked what was written below it....sorry about that.

[Billybeau1]

:thumbsup:

[ArisReef]

Thank you very much for your answers and the link ref.
Very useful ;)