Seametrics CT2X Conductivity Sensor With Depth Option

Seametrics CT2X Conductivity Sensor With Depth Option is a microprocessor-based submersible conductivity/temperature sensor with built-in data logging. This device stores thousands of records of conductivity, temperature, salinity, and total dissolved solids (TDS). The CT2X is also available with a depth/level option giving added functionality in the same sensor housing. The CT2X incorporates 4-pole electrode cell measurement technology for conductivity, salinity, and TDS.

This technology reduces fringe field interference errors, lessens inaccuracy caused by polarization effects, and lowers contact resistance problems. Four-pole electrode technology also allows users to work with one electrode over a wide range of conductivity. The conductivity element is constructed of epoxy/graphite, making it extremely durable for use in rugged field conditions. To clean, simply scrub with a small brush.

Seametrics CT2X Conductivity Sensor
Seametrics CT2X Conductivity Sensor

Seametrics CT2X Feature

  • Measures/Records conductivity, temperature, salinity, and TDS with a depth/level option
  • Low power
  • Modbus® RTU (RS485) and SDI-12
  • 0-300,000 μS/cm
  • Linear and nLFn temperature compensation
  • Small diameter — 0.75” (1.9 cm)
  • 349,000 records in non-volatile memory
  • Free, easy-to-use, new upgraded Aqua4Plus 2.0 software

Depth and level are measured with an extremely rugged and stable piezo-electric, media isolated pressure element and compensated for temperature using our proprietary calibration methodology. Temperature is measured using an epoxy bead thermistor. The CT2X is powered internally with two replaceable AA batteries.

Alternately it can be powered with an external auxiliary power supply for data-intensive applications. Several CT2Xs, or a combination of CT2Xs and other Smart Sensors, can be networked together and controlled directly from a single computer. While most will use the CT2X with our free, easy-to-use Seametrics Aqua4Plus 2.0 software, it is by no means limited to that software. You can use your own Modbus® RTU or SDI-12 software or logging equipment to read measurements, thus tying into your existing telemetry and control systems.


  • Wetland surveys
  • Saltwater intrusion monitoring
  • Agricultural runoff studies
  • Discharge monitoring

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Seametrics CT2X Specification

Housing & Cable Weight 1.0 lb. (0.5 kg)
Body Material Acetal & 316 stainless or titanium
Wire Seal Material Fluoropolymer and PTFE
Cable Submersible: polyurethane, polyethylene, or ETFE (4 lb./100 ft., 1.8 kg/30 m)
Desiccant 1-3 mm indicating silica gel
Field Connector Standard
Temperature Operating Range Recommended: -5 ̊ to 40 ̊C (23 ̊ to 104 ̊F) Requires freeze protection kit if using pressure option in the water below freezing.
Storage Range Without batteries: -40 ̊ to 80 ̊C (-40 ̊ to 176 ̊F)
Power Internal Battery Two replaceable lithium ‘AA’ batteries – Battery life: 12 months at 15 min. polling interval (may vary due to environmental factors)
Auxiliary 12 Vdc – Nominal, 9-15 Vdc – range
Communication RS485 Modbus® RTU (output = 32-bit IEEE floating point), SDI-12 (ver. 1.3) – ASCII
Logging Memory 4MB – 349,000 records
Logging Types Variable, user-defined, profiled
Logging Rates 4x/sec maximum, no minimum
Baud Rates 9600, 19200, 38400
Software Complimentary Aqua4Plus 2.0
Networking 32 available addresses per junction (Address range: 1 to 255)
File Formats .a4d and .csv
Output Channels Temperature Pressure¹ Conductivity
Element 30K ohm thermistor, Epoxy bead/external housing, Pyrex® glass Silicon strain gauge transducer316 stainless or Hastelloy Epoxy/Graphite – 4-pole
Accuracy ±0.25 ̊C ±0.05% FSO (typical, static) Static: ±0.5% of measured value (0 – 100,000 μS/cm)
±0.1% FSO (maximum, static)(B.F.S.L. 20 ̊C
Resolution 0.1 ̊C 0.0034% FS (typical) (32 bit internal) 0.1 μS/cm, 0.001 mS/cm, 0.1 mg/L (TDS), 0.001 PSU
Units Celsius, Fahrenheit, Kelvin PSI, FtH₂O, inH₂O, mmH₂O, mH₂O, inH₂O, cmHg, mmHg, Bars, Bars, kPa μS/cm, mS/cm, mg/L, PSU
Range -5 ̊ to 40 ̊C (23 ̊ to 104 ̊F) Gauge PSI: 1²,5,7,15,30,50,100,300 Conductivity1: 0-300,000
FtH₂O: 2.3²,12,35,69,115,231,692 μS/cmTDS: 4.9-147,000 mg/L
mH₂O: 0.7²,3.5,5,10.5,21,35,70,210 Salinity: 2-42 PSU
Absolute² PSI: 30, 50, 100, 300
FtH₂O: 35, 81, 196, 658
mH₂O: 10, 24, 59, 200
Compensated 0 ̊ to 40 ̊C (32 ̊ to 104 ̊F) Thermal: None, Linear, or nLFn
Compensated 200 msec
Max operating pressure 1.1 x FS
Over pressure protection 3x full scale up to 300psi
Burst pressure 1000 psi (approx. 2000 ft or 600 m)
Environmental IP68, NEMA 6P

*Specifications subject to change. Please consult our web site for the most current data ( Modbus is a registered trademark of Schneider Electric. Pyrex is a registered trademark of Corning Incorporated.

1 Accuracy reduced at levels <10 μS/cm and >100,000 μS/cm
2 ±0.25% accuracy FSO (max) at this range
3 Depth range for absolute sensors has 14.7 PSI subtracted to give actual depth allowed