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View Full Version : "temp and pH probes are supposed to be within 6 inches of each other"


kenargo
05/03/2007, 01:02 PM
On another thread it was mentioned that:

"The temp and pH probes are supposed to be within 6 inches of each other. The temperature probe is the ground reference for the pH"

I was unable to locate this information in my manual. How could this be? If this where the case then the PH probe would not read when you didn't have a temp and PH probe (as would be the case when the PH probe is in a Kalc reactor). It would also mean the probes are introducing current into the water.

I could image that if you wanted accurate temperature compensation for PH you want them close but I wouldn't expect the probe to be the ground reference.

Curt?

RWillieK
05/03/2007, 02:28 PM
I think the temp an pH probe need to be close for the temperature compensation to work correctly on the pH probe. Otherwise the temp might be much different than where the pH probe is, thusly changing the measurement correction.

Robbie

kenargo
05/03/2007, 02:43 PM
Yes, that was what I thought as well but the post indicated a different reason that didn't make sense to me.

RWillieK
05/03/2007, 03:46 PM
I don't think the temp probe could be a ground reference - its coated in rubber/plastic.

cali_reef
05/03/2007, 04:01 PM
<a href=showthread.php?s=&postid=9870124#post9870124 target=_blank>Originally posted</a> by RWillieK
I don't think the temp probe could be a ground reference - its coated in rubber/plastic.

Not the temp sensor for the ACIIIPro.

I think only the ACIIIPro uses the Temp sensor as a ground reference and the ph Probe needs to be close to it.

clp
05/03/2007, 04:42 PM
Only the ACPro and the AC3Pro use the temperature probe as a ground reference. On these controllers we recommend that the temperature probe is placed within 6" of the pH or ORP probes. There no placement restrictions on the AC3, PX1000, ACJr's temperature probe.

Curt

kenargo
05/03/2007, 05:17 PM
"Only the ACPro and the AC3Pro use the temperature probe as a ground reference"

Curt, are you saying that the temp prob has an electrical connection to the water so that it can create a ground loop? I thought that all the wet parts where fully insolated.

clp
05/03/2007, 05:35 PM
It is not a ground loop; it is a reference. It is just the way the analog circuitry in the Pro units has been designed.

Curt

kenargo
05/03/2007, 05:52 PM
Are you saying that there is a small current between the 2 probes (the reference)?

clp
05/03/2007, 05:56 PM
No, there is no electrical current flow. The 3Pro ground plane floats to the ground potential of the tank.

Curt

collins
05/04/2007, 08:08 AM
I was the one that posted the 6" reference. I have a pro unit, read that in the manual and tried to help matt the fiddler with his problem.

I thought that all the controllers would share this trait. Sorry to freak everyone out.

lvreefer
05/04/2007, 10:36 AM
Thanks for the clarification!!