Review on 🐠 SunGrow Refractometer for Aquarium Salinity Measurement - Highly Accurate, Calibration Tool Included, Promotes Optimal Plant and Marine Life Health, User-Friendly and Readability Enhanced by Cheryl Bailey

The reading was accurate prior to using the calibration solution and has therefore been accurately calibrated. Easy to use, solid construction, would recommend. If you are confident that they are calibrated correctly, consider purchasing a calibration solution. The solution itself is not expensive, but it is not cheap either. I couldn't find a small amount, if they included a tiny amount of eyedropper solution and added $5 to the total price that would be awesome! Much more convenient and to my knowledge the only brand that offers a "complete" kit.