faulty ph pen

[Ryan Thang To]

Hi
is my ph pen faulty if I calibrate it with ph buffer 6.8 and then buffer 4.0, I get a reading of 4.3 so I turn it down to 4.0 and then test it again with buffer 6.8 I get a reading of 6.5

Cheers ryan

 

[Claire]

Do you have the yellow one? I got this one the other day and mine does the same. Seems to be notoriously unreliable as I have tested a tank a couple of times and got .5 difference over a spell of 2 minutes! Have gone back to using liquid tests for pH in my malawi tank as I am thoroughly unconvinced with it.

 

[John S]

I think the issue is these are only single point calibration. I calibrate mine to the closest range I'm interested in which is 6.8,


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[Ryan Thang To]

Hi yes It's the stupid yellow one that I didn't know it was coming from china. Took almost 3 week to arrive.
There is another one look exactly the same but at the back is has 2 screw for calibrate. I call co2 art as they have the same one I have and they said they never had a customer complain about it so I Might again

 

[Ryan Thang To]

I think the issue is these are only single point calibration. I calibrate mine to the closest range I'm interested in which is 6.8,


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Yeah I notice a video on youtube wich has 2 screw for calibrate

 

[Claire]

I calibrated mine to the 6.9 solution and then went to test my malawi tank which I know sits around pH 8 and it was saying it was 9.8 haha.

 

[Ryan Thang To]

I calibrated mine to the 6.9 solution and then went to test my malawi tank which I know sits around pH 8 and it was saying it was 9.8 haha.

Same here. Both my shrimp and discus tank showing 8.0 lol