New Grower What to believe with pH, Drops or Pen?

[Slow2Gro]

Well I'm having issues with pH'ing water.
My drops are telling me one thing and my pen is telling me another.
When I put my Pen into 7.0 calibration solution it tells me it's 7.0, but the drops color looks closer to 6.0.
So which should I believe?

 

[JM]

believe the drops... do you know how to calibrate the pen?

how long have you had it?

 

[Slow2Gro]

Yeah I've calibrated the pen. I calibrated it to 7.0 (was at 7.2) then put it in water. Water said 6.5 then and I used drops and was told it was between 6.0-6.5 (color blind so I can't tell). So I'm guessing the pen is really close possibly. I was told the color wasn't the 6.5 shade, but could be close and the pen said 6.5.
It's a cheap Milwaukee pen btw (got it a few weeks ago). I've had the drops for over a year, so wasn't sure if they could go bad.
Thanks for clearing that up JM. I'll go by the Drops.

 

[gooseberry]

With colour test kits that you analyse by eye it can be quite important how you take the "measurement". Do it in good light, and with a good white background behind, I find that a tile is better than a piece of paper. Looking through the solution to the colour chart can help too.

Buffer solutions used for calibration can also get contaminated and "go off", usual practice is to use a small aliquot of buffer each time and discard it afterwards. Cleaning of the pH electrode between measurements (including buffers) and storage are also important (many need to be stored in a saturated KCl solution).

Perhaps the most important issue, given the many and varied ways that there are of measuring soil pH, is following the same procedure every time.