PH pen questions

[Stevef111]

Hey everyone I have an Oakland ph pen about 1 yr old and I just bought a ph200 from hydrofarm I calibrated both with brand new calibration fluid everything was ok I dipped my water and both pens read different I put them both in the calibration fluid and they read ok now what one do I believe ? Or is there a way to tell what on is right, the reading are 6.00 on hydrofarm and 5.72 on Oakland.

 

[TurboBucket]

Interesting. That's a pretty big difference for calibrated pens.

Does one use temperature correction where the other does not? If you leave the pens in the solution do they even out? Sometimes it feels like it takes forever for my pen to decide on a reading.

 

[Stevef111]

Both do the temp but I dipped them about 20 mins ago my Oakland read the 7 and the ph 4 was at 4.64 so I am thinking my Oakland is scrap

 

[TurboBucket]

You should be able to calibrate it. Check your manual. Or Google the make and model

 

[TorturedSoul]

I'm guessing you used to same pair of calibration solutions for both, but one of them uses the other set, the set that has pH 6.86 instead of 7.00?

 

[Stevef111]

Both are 7.00 and 4 for calibration

 

[MickFoster]

No calibration required and it's never wrong......been using the drops for over 25 years without a problem.

 

[Bush Doctor 77]

Are you rinsing off your probe after every reading, and blotting it dry before taking another reading? Accurate pH meters are expensive.