Review on 🌊 Aqua Craft Standard Seawater 35 ppt Refractometer Calibration Solution - Accurate and Convenient 60 ml Solution by Adam Nelson

I've been using this solution for years and the last few times I've gotten new bottles the results have been mixed. The bottle I just bought was 4 ppt lower than the 2 solutions I know were correct. Unfortunately, this has become inconsistent. I enjoyed using it because of the simplicity with the integrated bottle and dropper. Unfortunately, there seems to be a quality control issue somewhere. Of the last 2 bottles I bought, 2 were right and 2 wrong. One bottle showed 37 ppt and the last bottle showed 31 ppt. I think I'll create my own standard again and use empty bottles to store it.