One device, every key parameter
DO, pH, ORP, TDS, conductivity, salinity and temperature in a single meter — no rack of separate instruments.
Know your water before the fish do — a multi-parameter water quality tester that reads dissolved oxygen, pH, ORP, TDS, conductivity, salinity and temperature in one device, in handheld and online versions, so you can catch a crash before it costs you a tank.
15+ years in aquaculture engineering · Trusted by Japfa Group, Japan Nissui & Tropo Farms · Shipped worldwide in one container
Product Description
Advantage:
● pH glass electrode measurement method, applied to various PH/ORP monitoring and dosing control occasions;
● Support a variety of installation methods, wall mounting, pipe clamp installation, and panel installation;
● Clock and historical data recording function to meet higher data management requirements;
● Record 14,000 historical data and the recording interval can be set between 1 and 999 minutes;
● The protection grade of the enclosure is IP66;
● Two settable SPST multifunctional relays;
● Two high-precision 0/4~20mA current outputs;
● A two-wire RS485 interface, the communication protocol is MODBUS RTU;
● 128*64 large LCD screen, multiple languages available;
● The menu password can be set to facilitate hierarchical management;
● The meter can not only perform temperature compensation on the test sample, but also self-check the operating temperature of the instrument, compensate for the hardware temperature changes caused by temperature drift, and make the test results more accurate;
● Provide AC and DC power supply modes, both of them are the wide-voltage power supplies.








Specifications
Model combinations integrated from industry practice — measuring ranges and accuracies are confirmed against SIGMA's actual instruments per order.
| Model | Capacity | Typical use | Core configuration |
|---|---|---|---|
| SIGMA-WT-P | Daily spot checks | ||
| SIGMA-WT-M | Comprehensive spot testing | ||
| SIGMA-WT-O | 24/7 continuous monitoring | ||
| SIGMA-WT-S | PLC closed-loop control |
| Measured parameters | Dissolved oxygen (DO) · pH · ORP · TDS · conductivity · salinity · temperature (per model combination) |
|---|---|
| DO sensing | Optical fluorescence (stable, low-maintenance, preferred) or electrochemical |
| Form factors | Portable handheld meters and online/inline probes |
| Water type | Freshwater / saltwater |
| Display & data | Digital display with data logging; control models add alarm and control outputs |
| Protection | IP-rated housings for humid farm environments |
| Options | Calibration solutions, spare electrodes/probes, remote monitoring, PLC integration |
System composition
DO, pH, ORP, TDS, conductivity, salinity and temperature in a single meter — no rack of separate instruments.
Fluorescence sensors give fast, stable dissolved-oxygen readings with minimal recalibration — the parameter that matters most in high-density RAS.
Spot-check patrols plus 24/7 inline monitoring cover the whole farm.
Connected models feed a controller to trigger oxygen, aeration or alarms automatically.
IP-rated, fresh- and seawater probes stand up to humid farm environments.
Water-quality trends are recorded, so problems are flagged early and decisions are data-backed.
Application
Video
FAQ
A single meter reads dissolved oxygen (DO), pH, ORP, TDS, conductivity, salinity and temperature, available as portable handheld units for spot checks or online/inline probes for continuous 24/7 monitoring.
In high-density RAS an oxygen crash moves fast and DO is the parameter that matters most. Optical (fluorescence) DO sensors give fast, stable, low-maintenance readings so you can act before a problem becomes a loss.
On connected models the data can be logged, displayed and wired into a controller to trigger oxygen, aeration or alarms automatically.
Yes — probes are built for both fresh- and sea-water, and the rugged, IP-rated housings stand up to humid farm environments.
Tell us your species, target density and site — our engineers size the system and reply within one business day.