The Apera SX731 (AI467) is a professional 7-in-1 handheld water-quality meter designed for commercial cultivation, hydroponics, fertigation, and water-treatment applications. Using three interchangeable electrodes, it measures pH, oxidation-reduction potential (ORP), electrical conductivity (EC), total dissolved solids (TDS), salinity, resistivity, and temperature. The complete kit includes a 201T-S pH/temperature electrode, a 301Pt-S platinum ORP electrode, and a 2301T-S Brush-resistant Platinum Black (BPB) conductivity/temperature electrode.
The SX731 is designed for field use, with an IP57-rated housing, automatic electrode recognition, digital filtering, and onboard storage for up to 400 measurement records. Its wide conductivity range of 0–200 mS/cm accommodates both low-conductivity reverse-osmosis (RO) water and concentrated nutrient solutions. Automatic temperature compensation supports consistent readings, while the dedicated ORP electrode enables monitoring of oxidation-reduction potential in water-treatment and sanitation programs. The kit also includes calibration solutions and a rugged carrying case for convenient transport between testing locations.
• Product Type: Handheld multiparameter water-quality meter kit
• Brand: Apera Instruments
• Model: SX731
• SKU: AI467
• Measurement Parameters: pH, ORP (mV/EH), EC, TDS, salinity, resistivity, and temperature
• pH Measurement Range: 0.00–14.00 pH
• pH Accuracy: ±0.01 pH
• ORP Measurement Range: −1999 to +1999 mV
• ORP Accuracy: ±0.1% full scale for the meter; ±15 mV overall system accuracy
• Conductivity Range: 0.00 µS/cm to 200 mS/cm (200,000 µS/cm)
• Conductivity Accuracy: ±1% of full scale
• Temperature Compensation: Automatic (ATC), 0–50°C
• Included pH Electrode: 201T-S combination pH/temperature electrode
• pH Electrode Construction: Lithium-glass membrane, single ceramic junction, and integrated temperature sensor
• pH Electrode Operating Range: 0–14 pH; 0–80°C
• Included ORP Electrode: 301Pt-S platinum-ring ORP electrode
• ORP Reference System: Ag/AgCl reference with a single ceramic junction
• Included Conductivity Electrode: 2301T-S conductivity/temperature electrode
• Conductivity Sensor Technology: Brush-resistant Platinum Black (BPB)
• Conductivity Cell Constant: K = 1.0
• Electrode Recognition: Automatically detects the connected electrode and selects the appropriate measurement mode
• pH Calibration: Automatic 1–3-point calibration with recognition of U.S., NIST, and Chinese buffer series
• Conductivity Calibration: Automatic one-point calibration using a recognized conductivity standard
• ORP Calibration: No meter-level calibration required; proper electrode conditioning is necessary
• Low-Conductivity Measurement: Nonlinear automatic temperature compensation activates below 10 µS/cm to support measurements in near-pure and RO water
• Data Storage: Up to 400 measurement records
• Data Recall: Stored readings can be reviewed directly on the meter
• Digital Filtering: Helps improve measurement stability and reduce noise in field conditions
• Additional Functions: Electrode self-diagnosis and automatic power-off
• Water and Dust Protection: IP57-rated housing, designed for dust-tight protection and temporary immersion
• Included Calibration Solutions: pH 4.00, 7.00, and 10.00 buffers, plus a 1,413 µS/cm conductivity standard
• Other Included Accessories: Three electrodes, rugged carrying case, and supporting electrode-care accessories
• Primary Applications: Nutrient-solution testing, source-water verification, reservoir monitoring, runoff analysis, and water-treatment checks
• ORP Applications: Evaluating oxidizing capacity in sanitation and water-treatment solutions using peroxide-, chlorine-, or ozone-based treatments
• Suitable Growing Systems: Hydroponics, coco coir, deep-water culture (DWC), and recirculating hydroponic systems
• Warranty: 3 years for the meter and 6 months for the electrodes
• Important Limitation: The included conductivity electrode measures up to 200 mS/cm.
Key Advantage: The Apera SX731 combines pH, ORP, and conductivity testing with TDS, salinity, resistivity, and temperature measurement in one portable kit. Its broad conductivity range allows operators to test both low-conductivity source water and concentrated nutrient solutions without changing conductivity probes. Automatic electrode recognition simplifies switching between measurement types, while IP57 protection and 400-record data storage make it practical for routine quality-control checks across multiple reservoirs and cultivation areas.