johns
Premium Member
I've had this Aquacontroller Jr for only about 2-3 weeks. I purchased it new from Premium Aquatics, along with a lab grade pH probe. I have thought since day 1 that something is wrong with the pH reading I am getting as they are way off from both the pinpoint monitor probe I have been using as well as Salifert test kits. But I wanted to spend the first couple weeks figuring out the programming functions and getting all that set up. Now that I have at least a simplified program going I would like to finally tackle this pH problem. So...
Historiically, my pH has always read around 8.0-8.1 mornings to about 8.3-8.4 evenings. This is with a pinpoint pH monitor that I have in the tank. The Neptune readings have generally been about 0.4 - 0.5 units lower than this. As a low point I get 7.5, and on the high end about 7.9. I have calibrated the thing with Orion pH buffers at least 12-15 times over the past few weeks. I gave Neptune the benefit of the doubt until I could do a few more tests.
Here's what I did this morning. I swapped the Neptune probe on the AC Jr. with the Pinpoint Monitor probe I had been using as well as an extra pinpoint probe I have had sitting aside. I believe in reproducibility, so I swapped them each 3 times. Each time the probes were swapped I recalibrated the meter.
Initial readings:
Salifert 8.0
Pinpoint Monitor - 8.02, checked calibration in solutions, none needed
AC Jr. - 7.52, recalibrated - 7.64
First switch:
Switch to PP1 probe and recal - 7.94
Switch to PP2 probe and recal - 7.92
Switch back to Neptune probe and recal - 7.60
Second switch:
Switch to PP1 probe and recal - 8.02
Switch to PP2 probe and recal - 7.97
Switch back to Neptune probe and recal - 7.62
Third switch:
Switch to PP1 probe and recal - 8.01
Switch to PP2 probe and recal - 7.99
Switch back to Neptune probe and recal - 7.64
The entire time, the Pinpoint monitor was reading 8.02 - 8.04 with probe PP1 (I checked every time PP1 was not inserted on the AC Jr.) So, it seems that the AC Jr. readings match the readings of the Pinpoint Monitor pretty well when I use the PP1 and PP2 probes. They match the Salifert test pretty well also, I might add.
In my opinion something may be wrong with this Neptune pH probe. The pH reading are consistant, but I dont even have faith in the readings, let alone the idea of controlling my entire tank based on them. I feel this is too much to put up with for a brand new lab grade probe. Please let me know what you think and how I should proceed.
Historiically, my pH has always read around 8.0-8.1 mornings to about 8.3-8.4 evenings. This is with a pinpoint pH monitor that I have in the tank. The Neptune readings have generally been about 0.4 - 0.5 units lower than this. As a low point I get 7.5, and on the high end about 7.9. I have calibrated the thing with Orion pH buffers at least 12-15 times over the past few weeks. I gave Neptune the benefit of the doubt until I could do a few more tests.
Here's what I did this morning. I swapped the Neptune probe on the AC Jr. with the Pinpoint Monitor probe I had been using as well as an extra pinpoint probe I have had sitting aside. I believe in reproducibility, so I swapped them each 3 times. Each time the probes were swapped I recalibrated the meter.
Initial readings:
Salifert 8.0
Pinpoint Monitor - 8.02, checked calibration in solutions, none needed
AC Jr. - 7.52, recalibrated - 7.64
First switch:
Switch to PP1 probe and recal - 7.94
Switch to PP2 probe and recal - 7.92
Switch back to Neptune probe and recal - 7.60
Second switch:
Switch to PP1 probe and recal - 8.02
Switch to PP2 probe and recal - 7.97
Switch back to Neptune probe and recal - 7.62
Third switch:
Switch to PP1 probe and recal - 8.01
Switch to PP2 probe and recal - 7.99
Switch back to Neptune probe and recal - 7.64
The entire time, the Pinpoint monitor was reading 8.02 - 8.04 with probe PP1 (I checked every time PP1 was not inserted on the AC Jr.) So, it seems that the AC Jr. readings match the readings of the Pinpoint Monitor pretty well when I use the PP1 and PP2 probes. They match the Salifert test pretty well also, I might add.
In my opinion something may be wrong with this Neptune pH probe. The pH reading are consistant, but I dont even have faith in the readings, let alone the idea of controlling my entire tank based on them. I feel this is too much to put up with for a brand new lab grade probe. Please let me know what you think and how I should proceed.
