CT2X Conductivity Sensors Seametrics

The Seametrics CT2X Smart Sensor 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.

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.

Alternatively, 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.

Features :

  • Measures conductivity, total dissolved solids, and temperature
  • Ranges from 10 micro Siemens/cm to 100,000 micro Siemens/cm (200,000 and 300,000 micro Siemens/cm available on request)
  • Pressure and level options available
  • In-field calibration utilities
  • Narrow 0.75″ diameter, 12.5″ or 16″ length (depending on version)
  • Linear and nLFn temperature compensation
  • Up to 349,000 records in non-volatile memory
  • 316 stainless steel, fluoropolymer, and PTFE construction (titanium optional)
  • Digital industry-standard RS485 interface
  • Available with a variety of cable options—including polyethylene, polyurethane, and FEP Teflon
  • Modbus and SDI-12 protocols are available
  • Easy export to spreadsheets and databases

Specification :

Housing & Cable


1.0 lb. (0.5 kg)

Body Material

Acetal & 316 stainless or titanium

Wire Seal Material

Fluoropolymer and PTFE


Submersible: polyurethane, polyethylene, or ETFE (4 lb./100 ft., 1.8 kg/30 m)


1-3 mm indicating silica gel

Field Connector



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)


Internal Battery

Two replaceable lithium ‘AA’ batteries - Battery life: 12 months at 15 min. polling interval (may vary due to environmental factors)


12 Vdc - Nominal, 9-15 Vdc - range


RS485 Modbus® RTU (output = 32-bit IEEE floating point), SDI-12 (ver. 1.3) - ASCII



4MB - 349,000 records

Logging Types

Variable, user-defined, profiled

Logging Rates

4x/sec maximum, no minimum

Baud Rates

9600, 19200, 38400


Complimentary Aqua4Plus 2.0


32 available addresses per junction (Address range: 1 to 255)

File Formats

.a4d and .csv

Output Channels






30K ohm thermistor, Epoxy bead/external housing, Pyrex® glass

Silicon strain gauge transducer
316 stainless or Hastelloy

Epoxy/Graphite - 4-pole


±0.25 ̊C

±0.05% FSO (typical, static)
±0.1% FSO (maximum, static)(B.F.S.L. 20 ̊C

Static: ±0.5% of measured value (0 - 100,000 μS/cm)


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


Celsius, Fahrenheit, Kelvin

PSI, FtH₂O, inH₂O, mmH₂O, mH₂O, inH₂O, cmHg, mmHg, Bars, Bars, kPa

μS/cm, mS/cm, mg/L, PSU


-5 ̊ to 40 ̊C
(23 ̊ to 104 ̊F)


PSI: 1²,5,7,15,30,50,100,300
FtH₂O: 2.3²,12,35,69,115,231,692
mH₂O: 0.7²,3.5,5,10.5,21,35,70,210

Conductivity1: 0-300,000
μS/cmTDS: 4.9-147,000 mg/L
Salinity: 2-42 PSU


PSI: 30, 50, 100, 300
FtH₂O: 35, 81, 196, 658
mH₂O: 10, 24, 59, 200



0 ̊ to 40 ̊C (32 ̊ to 104 ̊F)

Thermal: None, Linear, or even




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)



*Specifications subject to change. Please consult our web site for the most current data (seametrics.com). 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

Reference :