Web Analytics Made Easy -

CTSTestr (Conductivity, TDS & Salinity)

I-1400 CTS Testr Overview

Analyte Range Resolution Accuracy
Conductivity 0.0 - 200.0 µS
200 - 2,000 µS
2.00 - 20.00 mS
0.1 µS
1 µS
0.01 mS
± 1% full scale
TDS 0.10 - 10.00 ppt
0.0 - 100.0 ppm
100 - 1,000 ppm
0.01 ppt
0.1 ppm
1 ppm
± 1% full scale
Salinity 0.00 - 10.00 ppt 0.10 ppt ± 1% full scale
Temperature 0 - 60°C (32 - 140°F) 0.1°C / °F ± 0.5°C (0.9°F) at 0 - 50°C (32 - 122°F)
± 1.0°C (1.8°F) at 50 - 60°C (122 - 140°F)

The 3-in-1 CTSTestr™ combination meter, catalogue number I-1400, is a portable, waterproof meter that measures Conductivity, TDS, and Salinity. Easy and quick to use, the CTSTestr features a large backlit, dot matrix display with easy to navigate menus for clear and easy reading and adjustment with up to 150 hours battery life. Shows parameter concentration and temperature readings simultaneously. Also displays indicators for battery life, readiness and calibration. Dedicated buttons for menu, calibration and display hold.

Automatic temperature compensation is featured for increased accuracy in different environments and sample sources. The unit can be calibrated both automatically and manually for conductivity, and with manual calibration for TDS and salinity. Also features a hold function to allow the pH meter to be removed from the solution without the reading on the display changing for ease of recording. User replaceable pin style sensor module allows for easy maintenance. The leakroof cap also acts as both a sample cup and a stablising base when standing the meter up vertically on a flat work surface. Chemical-resistant Valox body is rugged, dustproof, waterproof and IP67 rated. The top of the meter has a convenient plastic loop to allow for attachment of a variety of lanyards to prevent losing or dropper the meter. Comes in a convenient hard plastic carrying case, batteries and instructions.

Simply turn the meter on. Remove the protective cap from the tip of the probe. Dip the probe into the sample and stir the sample gently with the probe until the display stabilises. Calibration should be performed regularly (up to 3 conductivity points supported for automatic calibration), typically everyday that the meter is used. Factory calibrated against NaCl standards. Selectable TDS factor adds increased versatility.

CTSTestr is a trademark of Oakton Instruments. The CTSTestr™ is manufactured and guaranteed by Oakton Instruments, Inc. 1 year warranty on the meter. 6 months warranty on the electrode.


Feature Specification
Conductivity Calibration Automatic or Manual
Temperature Compensation Automatic (ATC)
Calibration Points 3 for Conductivity & TDS, 1 for Salinity
Normalisation Temperature (Conductivity) 25.0°C (77°F)
Temperature Co-efficient of Variation (Conductivity) 0.0% - 10.0%
TDS Factor 0.40 - 1.00 (selectable)
Power Source 4 x AAA 1.5 V batteries (included)
Battery Life > 150 hrs
Auto Shut Off 8.5 minutes from last key press
Ambient Operating Temperature 5 - 45°C (41 - 113°F)
Storage Temperature -20 - 60°C (-4 - 140°F)
Operating Relative Humidity 5% to 85% noncondensing
Waterproof IP67
I-1400 CTS Testr User Manual


The CTSTestr™ can be used for a wide variety of applications including aquaculture, hydroponics, fresh water aquariums, fish farms, swimming pools, industrial water treatment, wastewater treatment, drinking water, boiler blow-down, electroplating rinse tanks, the printing industry, and verification of reverse osmosis system operation.



Conductivity (or Specific Conductance) is a measure of water's capability to pass electrical current and is directly related to the concentration of ionised dissolved solids in water. The conductivity of pure water is very low and increases proportionally to the level of contamination present. Accurate conductivity measurement is extremely important in industrial water treatment applications. Conductivity is also frequently tested for in environmental applications. Conductivity SI units are Siemens per metre (S/m). This is often abbreviated to 'S'. Other units for lower levels of Conductivity are mS/cm (mS) and µS/cm (µS).

Conductivity can vary from 0.5 - 3 µS for distilled water, 2 - 42 µS for melted snow or rainwater, 50 - 800 µS for tap water, 100 - 1,000 µS for freshwater streams, 10,000 µS for industrial wastewater and 55,000 µS for seawater.


Total Dissolved Solids (TDS) and salinity concentrations of a water sample are often derived from the conductivity measurement. Water salinity influences the types of organisms that will thrive in a body of water as well as the plants that will grow on land fed by a particular water source.

TDS is a measure of the combined dissolved content of inorganic and organic substances in molecular, ionised or micro-granular suspended form, either volatile or non-volatile. The main application of TDS measurement is for water quality testing of groundwater. Sources of TDS frequently include agricultural and urban runoff, clay-rich soils, soil contamination and point source industrial or sewage treatment plant discharge. Total Suspended Solids (TSS) are defined as solids that cannot pass through a 2µm sieve.

Although TDS is not considered a primary pollutant, for aesthetic, taste and limescale considerations, the National Secondary Drinking Water Standard for TDS in the US is 500 ppm. The Specified Concentration or Value (SCV) for UK at the supply point is 2,500 µS/cm. The Specified Concentration or Value (SCV) for Ireland is also 2,500 µS/cm. The WHO has no evidence of adverse health effects up to 1,000 ppm, although such a value may not be acceptable to consumers.


Salinity seawater is a measurement of dissolved salts originating from soil and rocks. The ocean is on average 35ppt, and coastal areas tend to be less saline because of estuaries. Groundwater salinity levels are relatively low. Both temperature and salinity affect seawater density.

Water Temperature

Water temperature in freshwater and seawater influences many other properties of water such as pH, gas solubility which decreases with temperature (e.g. dissolved oxygen required for aquatic life), nutrient content and conductivity increasing with temperature. Elevated temperature can also result in algal blooms.