Don't settle for "close enough" when it comes to your reef’s salinity. Most hobbyist refractometers are designed for Brine (Sodium Chloride), which can lead to measurement errors of up to 1.5ppt in a reef tank. The Red Sea Seawater Refractometer is engineered specifically for the complex ionic content of Natural Seawater, providing the "Absolute Salinity" readings required for sensitive SPS and LPS corals.
While industry-standard refractometers are calibrated for salt brine at 15°C (59°F), the Red Sea model is calibrated specifically for Seawater at 25°C (77°F)—the exact temperature of a thriving tropical reef. This eliminates the need for complex conversion tables or temperature compensation math
Seawater-Specific Algorithm: Designed to account for the 70+ trace elements in seawater (Calcium, Magnesium, etc.), not just table salt.
High-Resolution Display: Focused specifically on the 0–40ppt range, giving you 2.5x the visual resolution of standard 0–100ppt scales for pinpoint accuracy.
Integrated ATC: Features Automatic Temperature Compensation to ensure accurate readings in varying room temperatures.
Dual Scale Readout: Easily view both Absolute Salinity (ppt) and Specific Gravity (S.G.) simultaneously.
Enhanced Optics: Features a high-quality glass prism and a light-diffusing cover plate for a sharp, easy-to-read boundary line.
Inconsistent salinity is a leading cause of coral stress and RTN (Rapid Tissue Necrosis). By using a tool specifically calibrated for 25°C/77°F, you ensure that your salt, alkalinity, and calcium levels are perfectly balanced, as these parameters all drift when salinity is measured incorrectly.
| Feature | Details |
| Calibration Solution | Natural Seawater (NSW) |
| Calibration Temp | 25°C / 77°F |
| Range | 0 – 40 ppt |
| Accuracy | +/- 1ppt / 0.001 S.G. |
| ATC Range | 10°C – 30°C (50°F – 86°F) |
| Includes | Protective Carry Case, Pipette, & Calibration Screwdriver |
Clean the prism with RODI water and dry with a soft cloth.
Apply a few drops of VASTOCEAN 35ppt Calibration Fluid (or RODI water for zeroing).
Wait 15 seconds for the temperature to equalize.
Look through the eyepiece and adjust the calibration screw until the line meets the 35ppt/1.0264 mark exactly.
