DuvinDD 18 Pack pH Calibration Solution Powder 6.86/4.00/9.18, pH Buffer Calibration Solution Packets for Precisely Calibrate pH Meter, pH Tester Calibration Powder Packets

Works exactly like it should product seems to be good for accurate calibration for a good price.

This pH calibration solution works as expected. Shipping was fast. The powders dissolve easily and I was able to calibrate my pH meter without any issues. The seller is also worth mentioning. They were helpful and responsive when I had a question. Good customer service is always a plus. Overall, a solid product and a good buying experience. I would definitely recommend.

This product adjusts the pH as described. Completely satisfied

Works as expected I hope but like others have said the crystals don’t dissolve very quickly for certain ph. I just mix and then come back a half hour later to mix again

Product is exactly as it is described to be. I actually took small water bottles, mixed a solution in each one and used those 3 bottles to calibrate my PH meter for over 5 months ths without the bottles dropping or rasing in PH.

The team was very adamant about ensuring that my pH monitor was satisfactorily calibrated... while the first few powders they sent did not dissolve properly and appeared to not calibrate correctly, they proactively reached out to verify it was working (without me even issuing a complaint) and sent replacement powders for free. The first set of replacements did not work, so they sent a second set of replacements, which worked well and calibrated my pH monitor as expected.

These are what they are. Calibrated my cheap pH meter for brewing and checking my mash pH.

Using a powder buffer solution is more tedious and annoying than a premixed solution, but this does a great job. The only issues I had was when the water temp was too cold for the powder to dissolve properly.