View Full Version : ph probe placement

01/14/2008, 03:28 PM
if i add a ph probe to a ca reactor is it ok to add it so it is sideways ( i would like to install it right after the pump output on a tee ( slightly extented tee so it isnt in the high flow of the pump)

or would it be better to put in in vertical from the topof the reactor ( i am worried about a co2 bubble getting stuck on the tip of the probe....

01/14/2008, 04:54 PM
Hmm, the probe itself isn't sensitive to oritentation, and I thought vertical placement was fine in general. Which probe is being used?

01/14/2008, 04:57 PM
havent decided yet mostlikely what ever comes with milwaukee ph controllor

dont these work off of a liquid inside the probe that slowly leaks out? inthat case dosnt it need to be vertical. even tho iv never read anywhere that they have to it seems logical.

Randy Holmes-Farley
01/14/2008, 05:05 PM
I recommend only sealed probes for hobbyists, but some refillable probes can leak through the small refill hole.

In general, the leakage through the glass bulb is negligible.

This article has more:

Measuring pH with a Meter

01/14/2008, 10:04 PM
is it ok to use them sideways. or even upsidedown

01/14/2008, 10:35 PM
I don't see why not. :)

01/14/2008, 11:07 PM
I am uncertain but the pH probes are filled with liquid or gel filling solution. There may be an air space of incomplete filling of the outer and inner reference electrode filling solutions. Putting a probe horizontal or upside down may expose the reference electrode to air rather than filling solution. My guess is the liquid or gel filled pH probes should be vertical.

01/14/2008, 11:15 PM

I may have to turn mine upside down and see if anything changes.

You know I'm a testing fool. :D

01/14/2008, 11:16 PM
i doubt it would be an instant difference

01/14/2008, 11:27 PM
Glass Electrode Schematic (http://en.wikipedia.org/wiki/Image:Glass_electrode_scheme.jpg)

Yeah I don't know if the change would be instantaneous but if you were mounting the electrode semi-permanently my guess is you would want it vertical.

We can await Billiy's test to see if there is a change:)

01/14/2008, 11:53 PM
OK, you talked me into it.

My pH is now 7.89

I just turned the probe upside down and will report in the morning. :)

I also turned my ORP probe upside down just for giggles. :D

01/14/2008, 11:58 PM
Hey I'd try it too but my Profilux pH probe instructions tell me not to get the cable / probe juction wet.

01/15/2008, 12:17 AM
yes the solutions inside were the concern.. but if it is FILLED then it really shouldent matter but if it is airin it like shown then i could see a problom... i guess ill just find a way to make it work ( maybe add an elbow to the tee i want to connect it to so it is always upright. but then again.. still worried about air bubbles....

Randy Holmes-Farley
01/15/2008, 05:50 AM
I would use a gel filled probe upside down, but not a liquid filled one. You need to be sure the internal reference electrode is submerged. There is typically air inside of refillable electrodes. Again, I recommend against them, and I do not think most hand held hobby probes are refillable.

01/15/2008, 10:27 AM
What would you expect the average lifespan of that Cole-Parmer gel-filled electrode you were using a few years back? Are you still using it? I find the refillable units to be more attactive for the long run, but really have no experience with their longevity.

Randy Holmes-Farley
01/15/2008, 10:51 AM
My probes have usually lasted until I broke them. Usually a few years. As long as you can calibrate it, it is working adequately. :)

01/15/2008, 10:57 AM
I'm inclined to buy this one then. I can bang it around my sump for a few years then. It reduce the risk of silver in the tank. A few extra bucks, but its submersible. Do the probes drift faster as they age?


01/15/2008, 10:58 AM
I should have reviewed that post I just made. Talk about bad grammer.

Randy Holmes-Farley
01/15/2008, 11:18 AM
That one looks like a fine choice for reef applications. :)

01/15/2008, 12:30 PM
Well, no change when I turned mine upside down. Except for a small decrease in pH which always happens to my tank overnight when the lights are out. 3 1/2 hrs after lights on. pH is back up to 7.90 :D

Randy Holmes-Farley
01/15/2008, 02:52 PM
Did you flip the meter upside down too? That's what they recommend when using them in Australia. :D

01/15/2008, 03:30 PM
I don't think that's true anymore. The global market means that all probes are now Australia-compatible. :)

Randy Holmes-Farley
01/15/2008, 05:22 PM
Ah, OK. Gald they fixed that. :D

01/15/2008, 08:50 PM
I think the real problem with Billy's experiment is that he is in Indiana...latitude ~40. No matter how he tilts the electrode it is ~45 degrees to vertical:D

Randy Holmes-Farley
01/16/2008, 05:45 AM
Hah, good point. I knew there was always something odd going on there.

01/17/2008, 12:12 AM

Page two. :D