AquaControl Jr. PH calibration issue

[KyleO]

I just got through setting up my new AquaController Jr. and calibrating the PH probe. I already had a PinPoint PH meter on the tank and when I stuck the AC Jr. PH probe in after calibrating I was very surprised to see quite a difference (Pinpoint reads 8.22 and the AC Jr. reads 8.06).

I calibrated both units again and tested the tank water against a chemical PH test and it reads closer to the Pinpoint. I do notice that the AC Jr. initial readings before setting the calibration set point is quite a bit off. The initial reading with the 10.01 calibration fluid is around 11.4 and the initial reading with the 7.01 calibration fluid is around 9.

I see that the AC Jr. adjusts down the the true PH level of the cal. fluid by measuring the calibration fluids after the calibration. After calibrating both units read the calibration fluids true (7 & 10) but disagree quite a bit when it comes to the tank water.

What the heck is going on?

Could it be the probe?

Anybody have experience and/or advice with this???

 

[oct2274]

when you calibrate it always is way off when you put it in the solution before you are done calibrating, mine does the exact same thing and i've had two different probes. Your pinpoint ph meter might be the one that is truely off. After calibrating is done and you stick it in the solutions it should be extremely close.

 

[KyleO]

<a href=showthread.php?s=&postid=11449459#post11449459 target=_blank>Originally posted</a> by oct2274
when you calibrate it always is way off when you put it in the solution before you are done calibrating, mine does the exact same thing and i've had two different probes. Your pinpoint ph meter might be the one that is truely off. After calibrating is done and you stick it in the solutions it should be extremely close.

Yes, my first thought was that the Pinpoint PH monitor was off......but, when I use the PH test kit, it looks like the Pinpoint is a lot closer.

After calibrating both the AC Jr. and the Pinpoint read the calibration solutions perfectly (7 & 10) but they differ greatly when it comes to measuring the tank water! How can that be??? I have tried swapping out probes and the readings are very different. The most likely cause is that one probe is way off.

The trick is to figure out if it is the brand new probe that I received with the AC Jr. or the 8 mo. old probe that has been working fine with the Pinpoint is the problem........

 

[oct2274]

that is strange, what ph kit are you using to test against them. i know the red sea one is very in accurate and always reads high for me.

 

[KyleO]

I have since contacted Neptune Systems per the vendor that sold me the AC Jr. unit and PH probe to see how to tell for sure.

On a side note........I am seriously hoping that the new probe is the problem...........I would much rather find out that my tank PH is 8.1 as opposed to 7.85 all this time.