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lvreefer
08/16/2006, 08:33 PM
I am currently running an ACIII with pH one in a calcium reactor to control Co2 and pH two in the sump for tank pH. It seems that I am getting a ground loop of some sort. I have tried putting the probes close together, putting probe two in the main tank, and moving the temp probe around - all have failed. My pH seems to stay about .20+ppm above normal on both probes. I have recalibrated the probes and currently the temp comp. is off.

...help...Curt...anyone...

Thanks

Pepbill
08/16/2006, 08:43 PM
Have you updated to the most recent firmware?

clp
08/17/2006, 05:36 PM
After calibration do the probes read 7.0 and 10.0 in the appropriate calibration solutions (AquaController in run display)? If so the controller is correctly calibration, and the reasons for the possible discrepancy include:

- inaccurate calibration solution - only use single use calibration packages.
- ground loop - not possible on the AC3 w/ an Ethernet connection. It can occur if there is a serial connection.

Curt

lvreefer
08/18/2006, 09:53 AM
Curt,

I use the pinpoint seperate calibration packets for probe calibration. Last night I calibrated both probes again and they seem to be a little better, however when I disconnect either one of the probes the other one still changes and settles at a different pH value. Then when I hook the second probe back up it goes back to the orignal value.

1SickReefer
08/20/2006, 06:51 AM
<a href=showthread.php?s=&postid=7964618#post7964618 target=_blank>Originally posted</a> by lvreefer
Curt,

I use the pinpoint seperate calibration packets for probe calibration. Last night I calibrated both probes again and they seem to be a little better, however when I disconnect either one of the probes the other one still changes and settles at a different pH value. Then when I hook the second probe back up it goes back to the orignal value.

Mine is doing the same exact thing. I have the latest FW and 2 probes, one in the Ca rx and the other in the sump. If I disconnect one of the probes my readings jump up about .15 - .20 when I reconnect it the readings drop.

I have calibrated the probes many times with pinpoint single packets, and just ordered new packets from Curt. I figured I'de give his packets a try before I really start screaming that my ACIII cannot be trusted when it comes to PH values and I start asking for replacements.

I have a hard time believing that my PH is dropping to a low of 7.64 at night and only reaching 7.94 during peak MH times. Esp when everything is happy in my tank esp my SPS who's polyps are fully extended. I also drip kalk 24/7 and have a fuge light on 24/7. So again very hard to beleive that my PH is 7.64

If I just touch the BNC connector on the ACIII my readings bounce all over the place. This is w/o disconnecting them, this is just putting a finger on the BNC.

All I can say is that I hope the new packets fix it.

1SickReefer
08/20/2006, 07:15 AM
I just went to my tank and disconnected the PH2 probe (the one connected to the ORP) and my PH1 shot up by .14 from 7.64 to 7.78....... connected it back up and my PH dropped back to 7.64

Curt, is there any reason why this is happening. I haven't even added Co2 to my reactor yet because of this problem.

It sucks that I have a very expensive controller and I'm loosing faith that it cant even keep proper PH readings.

lvreefer
08/20/2006, 03:48 PM
It is a bummer. I have done the same as you and still have the issue. It looks like my tank pH (pH2) reads .20 low and my CA reactor pH (pH1) reads .1 - .2 higher than it should.

clp
08/21/2006, 11:45 AM
What brand and style probes are you using? Have you clean the probes with a soft bristled toothbrush?

morty
08/31/2006, 08:57 AM
lvreefer and 1SickReefer:

Have either of you been able to fix this issue yet? I haven't set up my ACIII yet but intend to use it in the exact same way, and I am now concerned about this issue after reading your posts. If there is a fix please advise - thanks!

Morty

lvreefer
08/31/2006, 10:57 AM
Curt,

I am currently using two pinpoint standard grade pH probes. One is about 10-12 months old and the other is a couple of months old. I clean both every month with a soft tooth brush at the same time I calibrate.

Morty,

I still have the problem. As a temporary fix I have offset my program for the CR and for the tank pH I just add a .2 (in my head) to the display reading.

I have full confidence that Curt will find a solution.

1SickReefer
08/31/2006, 02:55 PM
Marty, lvl.,

I think mine are reading correctly now. Here is what I did,

I took both of my PH probes and put them in the 7.0 and calibrated the first probe, once the 7.0 was done, I took BOTH probes from the 7.0 and moved them both to the 10.0 where I continued calibrating the first probe.. once the first probe was calibrated I again took both probes and moved them to the 7.0 and began the calibration of the 2nd probe till I was done with the 10.0..

After I did the process above, I can take either probe and put it in either solution and they will read 7.0 or 10.0.

HTH

lvreefer
08/31/2006, 03:54 PM
Nice thinking. If there is any interference from the other probe, it will take it into account during the calibration process. I’ll give it a try and get back to posting my results later tonight.

morty
08/31/2006, 04:32 PM
Ditto on the clever thinking! When I get to the point of setting everything up, I'll also post my results.

I am setting up a 270g reef, and haven't even yet built the sump or started to cure the rock, so it may be a few weeks.

clp
09/01/2006, 10:20 AM
1SickReefer,
That is indeed a clever solution, and does sound like it will solve the problem.

Curt

1SickReefer
09/01/2006, 11:07 AM
lol, thanks guys, I guess doing it this way is helping to reduce any interference from the in-tank probe messing with the probe being calibrated because both probes were in the solution together....

And I also wanted to do everything I could before I went to Curt for replacements.

GL

strittmatter
09/01/2006, 11:12 AM
is this on the ACIII pro? I have an ACIII but i only have a spot for 1 ph probe. how are you all running 2?

I think i have an ACIII can remember right now.

1SickReefer
09/01/2006, 11:16 AM
It is in the ACIII, do you have a ORP probe?

You can run 2 probes at a time with the ACIII.

Either 2 PH,
1 PH 1 ORP

HTH

morty
09/01/2006, 12:26 PM
Correct, with the ACIII you have the option of connecting a second pH probe to the ORP connector, thus giving you monitoring/control of two separate pH's (but this takes away the option of monitoring ORP). I intend to do just this, with one probe going to a Ca+ reactor, and the other going to the tank's sump. The two will work together to regulate overall tank pH via controlling the Ca+ reactor as well as a kalk reactor.

I decided I will monitor ORP through a separate ozone generator/controller.

1SickReefer
09/01/2006, 12:28 PM
Or get the expansion box and use the ORP probe with it

Dom_P
09/01/2006, 07:28 PM
Guys I'm using an ORP probe. Just out of curiosity (I know it killed the cat, but I'm not a cat :)), I touched the ORP BNC connector on my ACIII and it dropped by about 8mv, then touched the pH one, and the ORP value dropped the same way.

I then shorted the pH BNC case to the ORP one using a screw driver, and got similiar results - ORP value dropped. Which really confused me. I was expecting no change - as I was guessing they were both at the same potential (but maybe just floating).

Curt, is this something you can reproduce?

clp
09/05/2006, 04:37 PM
I would expect the values to change a small amount when you touch the connectors. The pH and ORP probes are extremely high impedance, and when you touch the connectors you temporarily shift the ground reference, transfer electrical charge, etc. This electrical potential change or charge transfer causes current to flow through the probes and a small reading change. Just don't do that. :-)

Curt

Dom_P
09/09/2006, 12:02 PM
LOL. OK will do...

lvreefer
09/11/2006, 10:46 AM
FYI Update:

After calibrating both probes like 1SickReefer suggested, I have had readings that stay consitant and truer to standard reagent testing.

My quick question to Curt is. When I am using two probes, both pH, how should I setup the 2nd probe in the options menu. In other words does the settings for ORP in the options affect pH probe two like it does pH probe one (offset ect.)? Or should I uncheck the box?

clp
09/11/2006, 11:32 AM
No, the ORP settings do not affect the pH reading.

Curt

lvreefer
09/11/2006, 03:44 PM
Great. Thank you.

gman19
09/13/2006, 12:05 PM
I think this thread just sold me an ACIII...I've been considering one for the past couple months. The fact that one can run 2 pH probes simultaneously is a great PLUS!