Bluelab pH 4.0 & 7.0 Calibration Solution (500ml)

Not Much To Say. It's accurate! No Complaints Here!

I own the blue lab ph pen and EC meter, and these solutions are perfect for calibration of the pH pen. I bought large bottles, still working super well a year later, probably have enough to last me another 3 years of regular monthly calibration checks/calibrations. Between the nice test pen and these solutions my hydroponic results have improved. Good stuff.

the stuff if you follow directions it works just like it's supposed to it does exactly what it says it's going to do

Works perfect for recalibration of blue lab ph pen. What else could you ask for?

I does what it says and is reasonable on price