ORP Monitoring Question

[builderguy]

When setting up an ORP controller does it make sense to turn on the option for ph Calibration --- i.e. for the controller to take the pH into account to calculate value?

[Billybeau1]

I don't know what kind of controller you refer to but, no. It does not make sense.

Although there is a direct correlation between pH and ORP, I would not use pH to affect the ORP level. pH affects ORP but ORP does not affect pH, much.

You set your controller to whatever you want your desired ORP level to be and let the pH be what it is. :)

[builderguy]

ORP is higher when the pH is higher, if you use the pH compensation option. I just don't want to overdose my Ozone.

I have an Aquacontroller II.

[Billybeau1]

I'm afraid you've been misled.

As pH rises, ORP lowers and as pH lowers ORP rises.

Just set your ORP to your desired level and let the controller take care of itself.

Many target 390 as being the optimum level but I suspect anything between 350 and 400 should be ok. :)

[builderguy]

hmmm...When I turn "on" the option for pH compensation it shows a MUCH higher ORP value then when it's off.

[Billybeau1]

Without knowing the value at which the compensation feature uses, I'm not clear which to use.

If you will tell me the brand name of the controller, I can research it and see which is better for your tank. :)

[builderguy]

It's an Aquacontroller II

Thanks for the help

[Billybeau1]

I'm not familiar with that controller. I've got a shout out to Boomer. I'm sure he'll shed some light on the subject. :)

[Boomer]

Leave it off :D

Some meters may have what is called a rH correction which adjust for pH. Many think this correction is overcorrected giving higher ORP when it is on.

It follows a very old forumal

(rH = mV / 29 + (2xpH) + 6.67)

You and read about it in detail here

ORP and the Reef Aquarium
http://www.reefkeeping.com/issues/2003-12/rhf/feature/index.php

[builderguy]

Thanks guys...appreciate the help