Check the listing for details. 0-10% Handheld Salinity Refractometer Aquarium Sea Water Salt Hydrometer Tester. Condition: New. Listed at 17.99 USD. 0-10% Handheld Salinity Refractometer Aquarium Sea Water Salt Hydrometer Tester This dual scale salinity refractometer is used to measure, monitor and control the concentration of salt water and brine, especially useful for aquarium and marine applications. This high quality refractometer measures on 2 scales, Specific Gravity (D 20/20) and parts per thousand and replaces your poor quality and difficult to read hydrometer. With just a couple of drops of aquarium water you know exactly what your salinity is The usual salinity of the selected aqueous solutions : • 1.Fresh water --- 50 ppt Features: • Salinity Refractometer Measure Salt Water or Salinity of Water, ideal for Aquariums, Marine Monitoring, Agricultural, Gardening & Educational Purposes. • Automatic Temperature CompensationBuilt-in ATC, which Accounts for Changes in Ambient Temperature and Automatically Compensates Accordingly to Guarantee Consistently Accurate Readings. • Dual Salinity ScaleDual Scale 0-100 ppt(0 - 10 %) of Salinity and 1.000 to 1.070 Specific Gravity (0-10%). • Full Copper Chrome Plated DesignSturdy & Compact, the Eyepiece is in High Quality for Better Viewing, Adopting Optical Glass Lens Rather than Plastic Lens for Accurate Measurement. Specifications: • Measuring Range: 0-10% Salinity • Division: 0.2% Salinity • Accuracy: ±0.2% • ATC: 0-10°C • Reference Temperature: 20°C • Item Length: 17.2 inch • Item Weight: 3.5ounces Operating procedures: 1. Open the cover and clean the detection prism with a soft cloth. 2. Take the test solution, place it on the detection prism, gently close the cover to avoid air bubbles, and make the solution spread over the prism surface and put the instrument into the light plate. 3. Align the light source or the bright area, observe the field of view through the eyepiece, and turn the eyepiece to adjust the handwheel. 4. Make the blue-white boundary of the field of view clear, and the scale value of the boundary is the concentration of the solution.