DuvinDD 20 Pack pH Calibration Solution Packets 6.86/4.01 for Accurate and Easy Calibration of pH Meter, pH Standard Buffer Powder Solution

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.

I like using these powdered calibration packets, they are simple and straight to the point. You don't have to throw them out after 30, 60 or 90 days like the liquid calibration solutions tell you to. All you do is pour each packet into a cup with 250ml of distilled water, make sure its dissolved, insert the pH pen and hit calibrate. BOOM! Calibrated. Easy peezy, lemon squeezy! Highly recommend these packets.

Seem as described haven’t used yet

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

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

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.

I only use this product to test my pH pen to see if it's still accurate

These are always accurate and you can store the solution in a cool dark place for months on end. At roughly 75 cents a pack to make 250ml its cost about $3 to make a litre which cost $14.99 at the hydroponic store. So you save $12 mixing your own.

works good

Kit ph

Cheapest option ive found so far, accurate and very easy to use. Don't waste it. You can store the solution for couple weeks.

Works as it should