Review on High Accuracy Water Quality Tester - Pesonder PH Meter, Digital PH Meter with 0.01 PH Measurement Range for Household Drinking, Pool, and Aquarium Water. ATC Design in Blue. by Christine Radcliffe

Quick and easy calibration, quick readings. For me this needs to be calibrated every few uses by checking the ground flow. Always calibrate before each measurement if you need high accuracy. When making your calibration solutions, heat (a small amount) of the water you use to make these substances easier and faster to dissolve. After they're done, keep them in a closet or dark place (I think that helps) so you don't have to make new poo. Dilute the solution every time, keep it clean. I also taped up the huge holes on the back, other cheap pens had water in them before. If you have water, let it dry and it can be used when it is completely dry (give it at least a day or put it in a place where it dries very quickly). So far this is my favorite pH pen out of the many I have had in different price ranges. fastest calibration, fastest readings.