pH pen issue...

Oui ca fait un moment que je vois écrirte des valeur de ph très précise. Alors que le meilleur pH-mètre de labo que j'utilise au boulot (très cher) n'est en définitive pas a 0.1 prés. 0.2 serai plus juste, et cela fraichement étalonné. Le ph et fonction de la température aussi. Une précision de 0.5 ( à 20°c ) ne m'étonne pas. C'est même pas mal pour des pH-mètre pas cher.

granny, then you do it wrong, test them on calibration solutions, don't throw them out. Calibrate. Turn off both, same big glass of tap water. both in - reading. turn off. both to 4.0 calibration solution. reading turn off. both to 7.0 calibration solution . reading if any lies to calibration - this one is dead. small drop while delivering, could make your meter bad from the start.

Use both and split the difference! ^(that would do my head in though!)* Or....pick one pen and never use the other.

Go old school and get General Hydroponics pH Test Indicator, it never fails. I always test with my pen first then test again with the drops just to ensure I'm getting a correct reading.

Had the same issue so I said fuck pens (unless you have hundreds of bucks to spend, and then the pens become decent again haha) For less than I got a root farm pH test kit that uses a sample plus drops. Very accurate, very cost-effective. I'm not looking back! I think you can get similar tests for aquariums so lots of brand options out there 😎 good luck