Designed specifically for aquarium use to measure the salinity of natural sea water (NSW). Most handheld saltwater refractometers available in the hobby are designed and calibrated for testing brine solution, i.e. sodium chlorid...
The Captive Purity Refractometer is an incredibly accurate and easy to use device that eliminates the confusion associated with inexpensive hydrometers. Just place a couple of drops of water on the prism and hold to the light. Rea...