Conductivity meter & temperature sensor with a real-time reference - Star-Oddi

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DST CT salinity (conductivity) & temperature logger

Data Storage Tag Conductivity and Temperature


Key features

  • Small and cost effective conductivity meter
  • Mainly used as a stand-alone CT at monitoring stations or moorings
  • Dimensions only 50 mm x 15 mm
  • Available with a plastic protective housing for more flexible mounting options
  • Selection of different conductivity ranges up to 63 mS/cm


DST CT is the smallest salinity (conductivity) and temperature logger on the world market. The conductivity meter records the data in its internal memory with date and time stamp for each measurement.

The DST CT is supported by the SeaStar software and the Communication Box which serves as an interface between the logger and a PC. Communication between the logger and the Communication Box is wireless.

In SeaStar, the user sets the start time, start date and sampling interval before starting the recorder. Up to seven different intervals can be set for the same measurement sequence. This is especially useful when more frequent measurements are needed at a certain time period.

After recovering the DST recorded data is uploaded to SeaStar where results are displayed both in graphic and tabular form. After retrieving the data, the DST can be re-programmed and reused as long as the battery lasts.

A set of Communication Box and SeaStar software needs to be purchased with the first order.

Examples of Application

The DST CT can be used as a self contained data logger for sampling in the oceans for environmental data collection salinity and temperature.

The DST CT is suitable for various studies:

  • Oceanography
  • Marine biology & ecology
  • Freshwater inflow
  • Marine animal tagging (externally)

Star-Oddi can provide a special plastic protective housing for attaching to deployment lines, buoys, or moorings. For more information about accessories please click here.

Conductivity ranges

We offer three conductivity ranges:

Type I (3-37 mS/cm)

Type II (13-50 mS/cm)

Type L (0.5-5 mS/cm)

You can calculate the most suitable conductivity range for your study with our conductivity calculator.

Conductivity is a combination of salinity and temperature. The DST CTD is basically a conductivity recorder from which the salinity is calculated. To view the graphical display of the connection between conductivity, salinity and temperature for each conductivity type, click on the type names above.

For sensor types I and II the conductivity accuracy is defined as 4%  Full Scale (FS). The low conductivity sensor, type-L, has conductivity accuracy defined as 6% FS. Salinity is a calculated value where the dominating accuracy parameter is the conductivity, thus the salinity accuracy follows the conductivity, i.e. 4% FS for sensor types I and II, and 6% FS for type-L. As the salinity range varies with temperature so does the accuracy unit values (psu).

The variation of salinity range and accuracy unit value with temperature can be seen for each type below:

Type I

Type II
Type L


Please note that the conductivity sensors are sensitive and measurement accuracy can be affected by biofouling. The warranty does not cover issues concerning biofouling causing offset in salinity measurents, if not traceable to a production fault. In the SeaStar software it is possible to put in an offset value for salinity sensor, correcting salinity offsets.

To read more about possible reasons for biofouling and other causes please read FAQ

Technical Specifications

SensorsConductivity (salinity) and temperature
Size (diameter x length)15mm x 50mm
Housing materialAlumina (Ceramic)
Weight (in air/in water)in air: 21g
in water: 13g
Memory typeNon-volatile EEPROM
Memory capacity130,826 paired CT measurements
Memory capacity bytes392,478 bytes / conductivity-temperature 3 bytes
Memory managementCustom programming
Data resolution12 bits
Temperature resolution0.032°C (0.058°F)
Temperature accuracy +/-0.1°C (0.18°F)
Temperature range -1°C to +40°C (30°F to 104°F)
Temperature response timeTime constant (63%) reached in 20 sec.
Pressure tolerance2500m (please provide the depth you are going to use the logger at so the applicable membrane is applied)
Conductivity rangesAvailable ranges (customer specified):
0.3 to 5 mS/cm
3 to 37 mS/cm
13 to 50 mS/cm
Extended range:
13 to 63 mS/cm (surcharge applies)
Conductivity resolution0.01 mS/cm
Conductivity accuracy +/-1.5 mS/cm
Salinity rangeDepends on conductivity range selected
Salinity resolution0.02 PSU
Salinity accuracy+/-1 (PSU)*
Data retention25 years
ClockReal time clock
Accuracy +/-1 min/month
Sampling intervalIn second(s), minute(s) or hour(s)
Number of different sampling intervals1 to 7 intervals within same measurement sequence
CommunicationsCommunication Box, RS-232C 9 pin serial or USB
Attachment hole0.9 mm (in diameter)
Operational depthPre-defined by user when ordering.
Can be up to maximum 2400 m.
Battery life4 years **
Start date/time of recordingsAny future time. User programmable.
Application softwareSeaStar
* Based on conductivity full scale accuracy at 24°C.
** For sampling interval of 10 minutes.
Specifications may change without notice.

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