[Dan S]

I've been told in the past if you want to run your PH below 7.01 you should calibrate it with the 4.01 solution. So that is what I've always done with no problems.

 

[Dan S]

Izzy, Thanks for stepping in and providing this info. I too bought mine slightly used minus the instruction manual. You shed a whole new light on calibration! Luckily, I haven't had any trouble with my controller or my livestock since I've been using it for the last couple years! I guess i better buy some 7.01 solution!