you do not need to calibrate every 2 weeks...that is a waste of solution. I only calibrate when I start to see abnormalties in the reading's...most of the time I have to change the battery more often than calibrate.

the one bummer about buying a 4 in1 meter, is...If one goes done so do them all...goodluck, peace
latewood Reviewed by latewood on . Someone please explain... Can someone please explain the purpose of Ph buffers. Do you need them? Why are there specific amounts? Do they correlate with Ph up/down or IS ph up/down a buffer in its own? I bought a hanna 4 in one combo gro check. It came calibrated already but included Ph 4.01 and Ph 7.01 solutions for calibration? What are these packets? Do I need them? They are 20 mL each. Are these one time applications? Can I use them more than once? How do you store it if you can use it more than once because they Rating: 5