Refractometers for Aquariums

How to use a refractometer
A seawater refractometer uses the refraction of light in liquid to measure specific gravity. Place a few drops of water under the refractometer lid, close the lid, and point it at a light source. Look through the eyepiece for a change in color created by refracted light. The line will run through a chart inside the eyepiece that indicates the specific gravity.

A digital refractometer is even more precise than a mechanical refractometer.

Another option is a digital water tester, a handheld meter that combines a thermometer and salinity tester to make water changes a breeze.
10 Results
Hanna Instruments Marine Waterproof Salinity and Temperature Tester

Hanna Instruments Marine Waterproof Salinity and Temperature Tester

Marine Depot Aquarium Refractometer

Marine Depot Aquarium Refractometer

AquaMaxx REEFractometer Refractometer

AquaMaxx REEFractometer Refractometer

Milwaukee Seawater Digital Refractometer

Milwaukee Seawater Digital Refractometer

Digital 3-in-1 Water Tester - Salinity, Temperature, and TDS

Digital 3-in-1 Water Tester - Salinity, Temperature, and TDS

Red Sea Seawater Refractometer

Red Sea Seawater Refractometer

Hanna Instruments Digital Seawater Refractometer

Hanna Instruments Digital Seawater Refractometer

IceCap Salinity/Temperature Digital Pocket Tester

IceCap Salinity/Temperature Digital Pocket Tester

Milwaukee Seawater Digital Refractometer with Protective Hardshell Case

Milwaukee Seawater Digital Refractometer with Protective Hardshell Case

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