i swear by the PH 600, i broke mine by accident 1yr in service and holds a calibration for a while, your best bet with any digi meter is to have ph drops to double check, calibration for the meter is ultra easy, put in the 7.01 solution and use screwdriver on back to adjust to 7.0....you can even use the 7.0 solution, i have a ph53 meter that broke in a week so sometimes more expensive isnt always the best