Digital Refractometer for Seawater Analysis - HI96822 - Hanna Instruments

The HI96822 replaces the guesswork inherent in analog swing-arm or optical refractometers by measuring the refractive index of a water sample electronically and converting that value to salinity using physical seawater properties drawn from peer-reviewed scientific literature. Because the conversion model is based on actual seawater rather than sodium chloride, readings are accurate for natural ocean water, artificial reef salt mixes, and brackish systems alike — a meaningful distinction that generic NaCl-calibrated instruments cannot claim.

Three simultaneous output units — Practical Salinity Units (PSU), parts per thousand (ppt), and specific gravity referenced to 20/20 — mean the meter speaks the language of every reference table, research paper, or fellow hobbyist you consult. Automatic Temperature Compensation (ATC) eliminates the need to correct readings manually, and the 1.5-second response time keeps routine testing fast whether you're running multiple samples at once or checking a single display tank.

Construction reflects field and lab use. The stainless steel sample well resists corrosion from saltwater, and the sealed flint glass optical prism maintains optical integrity over time without the fogging or calibration drift that affects plastic-prism instruments. Cleanup is a wipe with a soft cloth — no rinsing protocols or air-dry cycles required between samples.

For users who want to verify meter accuracy, Hanna provides a straightforward NaCl standard solution protocol: a 3.5% NaCl solution (3.50 g NaCl in 100 g total solution) should return approximately 34 ppt seawater equivalent, and a 10% solution should return approximately 96 ppt. Note that these verification solutions use sodium chloride as a practical check standard, but the meter's salinity algorithm remains calibrated to true seawater properties, not NaCl. The HI96822 is appropriate for reef aquaria, marine research, aquaculture, and field collection work.