Compact Saltwater Salinity Pen

What It Is

The Apera 5052 (SKU: AI235) is a pocket-format saltwater salinity pen from Apera Instruments' Eco Series — a line built for fast, field-ready measurements without the bulk of benchtop instrumentation. The 5052 is purpose-designed for the elevated salinity ranges found in marine and saltwater environments, covering 0–100 ppt (equivalent to 0–100,000 ppm).

It measures practical salinity — not absolute salinity — derived from conductivity and converted using the Practical Salinity Scale 1978 (PSS-78), standardized against Normal Standard Seawater at S=35 and calibrated in conductivity ratio (K15). PSS-78 is the internationally recognized benchmark recommended by all major oceanographic organizations for reporting salinity data.

The sensor is a platinum-coated probe with automatic temperature compensation active from 32 to 140 °F — broad enough to cover the temperature variability in most operational environments. Single-button operation keeps field use straightforward, and the auto power-off and low-battery reminder functions reduce dead-meter surprises during high-throughput testing runs.

Who It's For

The AI235 fits operations that need a dedicated, high-range salinity instrument rather than a general-purpose multi-parameter pen. Aquaculture facilities — including recirculating aquaculture systems (RAS) and integrated aquaponic setups — require consistent seawater or brackish-water salinity checks to maintain species health and system stability. A pocket pen that delivers a verified reading in 10 seconds without sample collection or bench setup fits that workflow.

Environmental monitoring programs, water quality compliance checks, and water-sourcing verification are also on-label applications. Operations using seawater-derived mineral inputs or monitoring high-ionic-strength process water will find the 0–100 ppt range and the PSS-78 standard alignment useful for repeatable, reportable results.

The 5052 is also a clean upgrade path from hydrometers and optical refractometers in facilities that still rely on those tools — the dip-and-read method eliminates sample collection, air bubble errors, and parallax reading issues inherent to those older methods.

Key Features

Platinum-coated sensor with ATC: The proprietary platinum-coated conductivity electrode maintains accuracy across the full 0–100 ppt measurement range, with automatic temperature compensation running from 32 to 140 °F. No manual temperature correction needed between readings taken at different ambient conditions.

Minimal calibration burden: Monthly calibration is sufficient for reliable ongoing results — the calibration solution is included in the kit. For operations running daily salinity checks across multiple tanks or water sources, this cadence is practical without sacrificing result confidence.

Dip-and-read in 10 seconds: No sample cup required. Dip the pen directly into the water source and read — no rinsing required between successive tests. Auto power-off and low-battery alerts are built in. Powered by 2 × AAA batteries.

Complete kit included: Each AI235 ships as a complete kit — the 5052 tester, AAA batteries, calibration solution (50 mS/cm), and a carrying case. Warranty is 2 years on the instrument and 6 months on the sensor.

How It Fits a Build

For RAS and aquaponics-integrated grows, the AI235 belongs at every tank station where marine or brackish species are maintained — not in a drawer waiting for monthly QC. The 10-second read time and no-rinse operation mean a facility technician can move through a multi-tank environment without breaking stride.

Paired with Apera's broader pocket tester lineup (pH, EC/TDS, multi-parameter), the 5052 fills the dedicated high-range salinity slot that general-purpose EC or multi-parameter pens handle less precisely. If your operation's water chemistry program already includes Apera pH or conductivity instruments, the 5052 integrates into the same calibration-solution ecosystem and carries the same 2-year instrument warranty.

HSC supplies the AI235 nationally to licensed cultivation and aquaculture operations. Request a quote for unit pricing, volume tiers, or kit bundle options.