LAQUAtwin series is a compact water quality tester. Using Ion Specific Electrode (ISE) technology, they are available for Conductivity, Calcium ion, Nitrate ion, Potassium ion, Sodium ion and pH measurement.
Using just a single drop of liquid, the LAQUAtwin proprietary flat sensors can quickly and accurately measure the values of the chemical parameters for artificial seawater or freshwater requirements.

LAQUAtwin conductivity meter (B-771) can be used for seawater salinity
measurement. Take conductivity measurement of seawater then convert into
salinity concentration referring to the PSS-78 (Practical Salinity Scale of 1978)
conversion table.

*Automatic salinity conversion of B-771 is not based on PSS-78

Seawater salinity conversion table


Seawater salinity

45 mS/cm

29.1 PPT

46 mS/cm

29.8 PPT

47 mS/cm

30.5 PPT

48 mS/cm

31.3 PPT

49 mS/cm

32.0 PPT

50 mS/cm

32.7 PPT

51 mS/cm

33.5 PPT

52 mS/cm

34.2 PPT

53 mS/cm

35.0 PPT

54 mS/cm

35.7 PPT

55 mS/cm

36.4 PPT

With LAQUAtwin, quick and easy check of Ca2+ (B-751), Na+ (B-722), K+ (B-731) and pH (B-712) are possible. Error of measurement data to artificial seawater with LAQUAtwin is within ± 20%.

※ Chloride ion is one of interfering ions for nitrate ion measurement. Chloride ion in seawater or artificial seawater around 20,000ppm will affect the nitrate ion measurement of less than 500 ppm.

Measurement data of artificial seawater by LAQUAtwin

Meas. Item

Contents of Artificial
Seawater on the Label

Meas. Result
by LAQUAtwin

Error of Each Meas. Data to Label Value*

Conductivity (EC)


49 mS/cm



416 ppm

380 ppm

within ± 10%


9651 ppm

9800 ppm

within ± 10%


366 ppm

400 ppm

within ± 10%


pH 8.1~8.2

pH 8.0

within ± 10%

* The error may become larger for extremely conterminated samples.

LAQUAtwin EC-33: Click to enlarge

Flat sensor technology and 60 years of sensor engineering realizes a reliable and direct measurement of a drop of the sample from 0.12mL. No need for a beaker to calibrate or measure. Just drop the standards and sample on the flat sensor, saves you time and minimize wasting your precious sample. Conductivity readings can be converted into salinity and TDS.

LAQUAtwin pH-33: Click to enlarge

Accurate pH measurements in a few seconds, from a single drop.Whether you need to keep the pH of an aquarium within tight limits, are checking for the acidity of rain water or for the quality of meat and fish products, LAQUAtwin compact pH meters are ideal for you.