A refractometer is a tool that accurately measures the salinity of your aquarium water. It works by measuring the amount of light that is refracted, or bent, as it passes through the water. The amount of refraction is directly proportional to the salinity of the water.
To use a refractometer, you need to place a few drops of your aquarium water on the prism and close the cover. Then, look into the eyepiece in the direction of a light source and adjust the focus until you see a clear line between blue and white fields. The upper part of what you see should be blue, while the lower part should be white.
There are many different types of refractometers available for aquarium use. Some popular options include handheld salinity refractometers (analog) and digital salinity refractometers. Handheld salinity refractometers are cheaper and more commonly used than digital ones. They are easy to use and provide accurate readings. Digital salinity refractometers are more expensive but offer more features such as automatic temperature compensation and easier calibration.
When selecting a refractometer for your saltwater aquarium, it’s important to choose one that is appropriate for your needs. You should consider factors such as accuracy, ease of use, and price when making your decision.