The first thing is if your going to grow seriously is don't buy cheap meters, I bought a Hanna Champ Ph meter and had the same experience as you, Hanna Brand SUCKS. I ponied but some bucks and bought a Blue Labs Combo meter that has PH and you calibrate with the 7.01 and 4.01 solutions and the other probe is the PPM/EC/Temp.

The good thing is the PPM probe is already calibrated at the factory and won't fall out of its calibration. Haven't had any problems since getting a good meter.

__________________
He Who Hesitates is STONED!!!