PH calibration

[tavernkeeper]

regarding the calibration routines on the PH probe. When I do the calibration for 7.0 the number comes up in MV and does not get to 7. Should it or are we just looking for stability in the number? When I calibrate for 10 the calibration comes up in % and mine ranged from 98% to 99.1%. Whats the target? Does 100% mean its at 10 and why are the two different measurement units?
Thanks
Brian

 

[JeffB418]

regarding the calibration routines on the PH probe. When I do the calibration for 7.0 the number comes up in MV and does not get to 7. Should it or are we just looking for stability in the number? When I calibrate for 10 the calibration comes up in % and mine ranged from 98% to 99.1%. Whats the target? Does 100% mean its at 10 and why are the two different measurement units?
Thanks
Brian

You are just looking for the reading to stabilize, and it won't correlate to the pH value of the calibration solution. You can check after calibration by keeping the probe in the solution and looking at the reading on the main display. As for the % vs mV, that's most likely a bug. It shouldn't really matter since the main display is in pH. It most likely will be corrected in a future release.

 

[tavernkeeper]

Thanks for the response. Am really enjoying exploring all the options available.

 

[Don]

You are just looking for the reading to stabilize, and it won't correlate to the pH value of the calibration solution. You can check after calibration by keeping the probe in the solution and looking at the reading on the main display. As for the % vs mV, that's most likely a bug. It shouldn't really matter since the main display is in pH. It most likely will be corrected in a future release.

Actually the mV vs % is correct. In theory a pH probe in a solution of 7.0 pH should produce exactly 0 volts. This displays how many mV (millivolts) the probe is actually producing, which is an error signal. If the pH probe is in good shape, this number will be close to 0 and will display in green. As the number gets further from 0 it will change to Yellow and then to Red.

When calibrating 10.0 or 4.0 the display shows the percentage of theoretical value that is being read. Again, a perfect probe will show 100% and that will be in green. As the numbers move away from 100% the number will be in yellow and then red.

When the numbers are red, it indicates a probe that is possibly defective or is getting close to end of life.

Just as a reminder, the 4.0 and 10.0 calibrations both depend on the 7.0 calibration, so it is always better to do it first.

Also there is no need to even to a 4.0 calibration unless you expect values lower than 7.0 (like for a saltwater tank).
Similarly, there is no need to do a 10.0 calibration unless you expect numbers higher than 7.0 (like for a reactor).

 

[JeffB418]

Actually the mV vs % is correct. In theory a pH probe in a solution of 7.0 pH should produce exactly 0 volts. This displays how many mV (millivolts) the probe is actually producing, which is an error signal. If the pH probe is in good shape, this number will be close to 0 and will display in green. As the number gets further from 0 it will change to Yellow and then to Red.

When calibrating 10.0 or 4.0 the display shows the percentage of theoretical value that is being read. Again, a perfect probe will show 100% and that will be in green. As the numbers move away from 100% the number will be in yellow and then red.

When the numbers are red, it indicates a probe that is possibly defective or is getting close to end of life.

Just as a reminder, the 4.0 and 10.0 calibrations both depend on the 7.0 calibration, so it is always better to do it first.

Also there is no need to even to a 4.0 calibration unless you expect values lower than 7.0 (like for a saltwater tank).
Similarly, there is no need to do a 10.0 calibration unless you expect numbers higher than 7.0 (like for a reactor).

Awesome, thanks for the clarification!

 

[tavernkeeper]

Thanks Don I appreciate the clarification on the calibration issues. To take it a step further at what point would the probe be considered "bad"? It came as part of the Hydros 4 kit I just received. I dont want to overreact and assume anything is wrong with any of the equipment but neither do I wish to ignore a potential issue.
Thanks again,

 

[Don]

Thanks Don I appreciate the clarification on the calibration issues. To take it a step further at what point would the probe be considered "bad"? It came as part of the Hydros 4 kit I just received. I dont want to overreact and assume anything is wrong with any of the equipment but neither do I wish to ignore a potential issue.
Thanks again,

As long as you don't see the number in red during calibration I wouldn't worry about it.

 

[Rutrag]

I placed the probe into the calibration solution and waited until the reading stabilized, and then I went into calibration. I’m not sure that I did it right, but when I went right into calibration, the numbers floated all over the place.