Apera Instruments, LLC-AI1109 8oz. pH Calibration Buffer Solution Kit (pH 4.00, 7.00 & 10.01), plus 4oz 3M KCL Storage Solution for pH/ORP Electrodes

Excellent value for the money saved me from buying a brand new pH pen it calibrated my pen perfectly I'm very pleased with my purchase

No problems and performed as expected.

Bought other brand of of meter. It came with powder for calibration. Did not feel I got a stable reading, could not trust. These liquids made me more confident in accurate setting!

If you have one of Apera PH meters and you are using it because you know it's very accurate then you need to have calibration solution on hand and use it! This takes all of the guess work out of it. Pairs great with the PH60 to keep my plants living in a comfortable soup knowing they are able to get the nutrients they deserve. As a bonus you have to have the KCI liquid anyway to store the meter. The only crazy thing to me is that when you spend $100 on a pH meter that comes with the smallest bottle of storage solution practically making you have to purchase this right after spending a small fortune on the meter feels kinda predatory towards your customers. Why not include a bottle the same size as the calibration solution included there would be plenty of room in the case for it. I get it is just another source of revenue for the company. I'll still buy it because I trust it.

I finally got tired of messing with cheap pH pens, and got a good unit capable of three point calibration. I still had some 4.01 and 7.0 reference solutions, but needed some 10.0 to get the third point. This kit contained the 10.0 that I needed, as well as storage solution, and was priced right compared to other brands. The kit arrived in good shape, with each bottle sealed in it's own plastic bag. I used the solutions to condition the probe per mfg's instructions, and went through the calibration routine. After cal, I checked the readings with the solution I had on hand, and it was spot on, so I'm satisfied that the solution's are accurate.