Review on 🌡️ Highly Accurate Digital pH Tester Pen for Water Hydroponics – Pocket Size, 0.01 Resolution, 0-14 pH Measurement Range – Ideal for Household, Drinking, Pool, and Aquarium (Yellow) by John Roberts

So far so good, the meter comes with 3-point calibration buffers. Seems great for my purposes. Also, it cost $12. However, the probe's glass cover was shipped dry and the instructions do not advise the user on how to properly store the probe. My advice to anyone who has purchased this gauge is to fill the black cap with a small amount of Buffer 6.8 when storing it so the probe never goes dry. Ideally, a separate storage solution would be available, but a pH four or seven buffer solution would also work. usually an electrolytic solution with a known concentration of potassium chloride and silver nitrate. The meter measures the voltage difference between the reference solution and the measured solution and calculates the pH, so it is important that the solution in the flask remains the same as it was at the factory. By drying or soaking. B. distilled water, the solution can evaporate or leak out of the semi-permeable membrane (glass bulb) and change the composition of this reference solution, which prevents the meter from making accurate measurements. In short, when you are not using the meter, make sure to store the sensor in buffer solution 6.8, or buy a special solution for storing the pH sensor.