I have a Hanna Ph Checker Plus and twice have done two point calibration using the Ph4 and Ph7 solution mix that came with the meter. I have since purchased Ph7 and Ph10 buffer solution to do two point calibration with one calibration on each side of the measured water...theoretically the best way to calibrate.
I tried to do the two point calibration several times, soaked the probe in cleaner, rinsed, stored in storage solution, rinsed, and attempted to do the two point calibration with the 7 and 10, rinsing between calibrations. The Ph7 worked fine but when I went to the Ph10 for the second point, it eventually registered an error and only recorded the Ph7 calibration tag. I was able to do dual point at Ph4 and Ph7 as well as single point at Ph4, Ph7, and Ph10 without issue. I did find that when I used single point on any of the buffers that the other buffers measured incorrectly by around 0.2. After a few more failed identical attempts, I assumed that in my newbiness that I had messed up the probe so I ordered a new probe from Hanna.
I received the new probe from Hanna today. I rinsed it off, soaked it in storage solution for a few minutes (since I no longer have cleaner solution), rinsed, and attempted the same two point calibration process again. The calibration process with the new probe is slightly faster, but I still get the same error when attempting the second point calibration with Ph10. I re-read the directions and re-watched the video Hanna has for the two point calibration and found my calibration process exactly matches the Hanna process.
At this point I am thinking my first probe is fine so I stored both probes in solution. Does anyone else have the Hanna Ph Checker Plus that can give me some advice on the two point calibration using Ph7 and Ph10?
I tried to do the two point calibration several times, soaked the probe in cleaner, rinsed, stored in storage solution, rinsed, and attempted to do the two point calibration with the 7 and 10, rinsing between calibrations. The Ph7 worked fine but when I went to the Ph10 for the second point, it eventually registered an error and only recorded the Ph7 calibration tag. I was able to do dual point at Ph4 and Ph7 as well as single point at Ph4, Ph7, and Ph10 without issue. I did find that when I used single point on any of the buffers that the other buffers measured incorrectly by around 0.2. After a few more failed identical attempts, I assumed that in my newbiness that I had messed up the probe so I ordered a new probe from Hanna.
I received the new probe from Hanna today. I rinsed it off, soaked it in storage solution for a few minutes (since I no longer have cleaner solution), rinsed, and attempted the same two point calibration process again. The calibration process with the new probe is slightly faster, but I still get the same error when attempting the second point calibration with Ph10. I re-read the directions and re-watched the video Hanna has for the two point calibration and found my calibration process exactly matches the Hanna process.
At this point I am thinking my first probe is fine so I stored both probes in solution. Does anyone else have the Hanna Ph Checker Plus that can give me some advice on the two point calibration using Ph7 and Ph10?
