Bluelab pH 4.0 & 7.0 Calibration Solution (500ml)

I followed the directions to the letter and the calibration solutions worked perfectly. I feel so much better about my grow knowing the reading I am getting are true readings. The solution hand my Blue Labs OnePen with perfectly calibrated and fast results

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.

Fast delivery, quality products

I do not dislike anything about this product is my first time using this product with a blue lab pH pen I’ve got to say it’s worth the money both these are 16.9 fl oz. This will probably last me the next 12 months.

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