VIVOSUN PH Meter Digital PH r Pen 0.01 High Accuracy Water Quality r with 0-14 PH Measurement Range for Household Drinking, Pool and Aquarium, with ATC, White

I bought an older version from vivo sun and was ready measured, this one need to do it with the powder solution

The pH meter seemed fine at first, followed the instuctions to calibrate but it didn't work.

Awesome pen, cheap and accurate. Have had it two months now use it 2-3 times a week and haven’t had to calibrate it yet!!!!

I didn’t Expect it to work as well. when I use the drops and test it with that and then test it with the tool it’s pretty much the same very impressed well worth the price

I have not encountered the need for a battery replacement, indicating the product's high quality. Its construction imparts a premium feel, reminiscent of the top-tier calculators used in school algebra classes. Despite experiencing a few accidental drops, the device has proven durable with no discernible damage. Surprisingly, even the glass bulb has remained intact after these incidents. Additionally, the calibration process was relatively straightforward. The inclusion of three different calibration powders, to be mixed with distilled water for creating the calibration solution, enhances its user-friendly nature. However, a suggestion for improvement would be to include extra sets of calibration packs, as the current provision leaves little room for error, potentially rendering the product unusable in the event of a miscalibration without a backup option.