Quote Originally Posted by xm177e2
I calibrated the Milwaukee pH pen every time before using it.. it was always all over the place and did not give consistent readings. My GH pH indicator dye works fine with my nutrient solution. I always check the water after adding the nutes and the color is yellow. My pen came with the 7.01 calibration solution and I was calibrating it every time prior to using it. I just dont trust it, it doesnt correspond with the colors on the liquid test, it is way off. Trying to calibrate it to the ambiguous colors of the test liquid would be a shot in the dark and is not worth it.
You can test a clean cup of water with all the means at your disposal, (liquid test kit and ph pen) then, take the same cup of water to the local aquarium store and have them test it for ya. Will give you a very good idea which is correct. I suspect your ph pen's electrode is toast. Mine just took a dump yesterday, too.