The Fishies AccuraSea Seawater Reference Solution is a precise calibration solution designed to ensure the accuracy of your saltwater aquarium testing equipment. Made from real seawater that has been micron filtered and UV sterilized, this reference solution is adjusted with reverse osmosis water to achieve standard salinity levels (S = 35 or conductivity of 53 mS/cm at 25°C). It serves as an ideal tool for calibrating refractometers and swing-arm hydrometers, providing reliable readings that are crucial for maintaining optimal marine life conditions. This solution is particularly useful for reef aquarium enthusiasts who require a high level of precision in their water testing practices to ensure the health and well-being of their aquatic inhabitants.