HydroFIA alkalinity system | Flanders Marine Institute

Flanders Marine Institute

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HydroFIA alkalinity system

The HydroFIA alkalinity system is used to measure the total alkalinity of a water sample. Alkalinity creates a ‘buffer’ against large fluctuations in the acidity of the water. These flucutations can be attributed to amongst others industrial waste or climate change. As such, the alkalinity of the water will protect the aquatic fauna and flora to changes in acidity of the environment.

How does the HydroFIA alkalinity system work?

The CONTROS HydroFIA system is an automated total alkalinity (TA) analyzer. It is designed and manufactured by Kongsberg Maritime Contros GmbH. The basic design and principles behind the HydroFIA TA are presented in Li et al. (2013). The analyzer follows the Gran Titration methodology, a method where a specific amount of seawater sample is acidified using hydrochloric acid. During the addition of acid, the pH is continuously determined spectrophotometrically up to the end point of the titration. Afterwards, TA can be calculated based on the amount of HCl that was used to reach the end point. The analysis takes approximately 10 min.

Why use a HydroFIA alkalinity system?

The HydroFIA alkalinity system is used to determine the TA of a seawater sample. In general, TA can be described as the ability of the water to withstand changes related to the carbonate system (like acidification).

The Contros HydroFIA TA can be used on board of a research vessel and be connected to the vessel’s underway nontoxic seawater supply, but can also be placed in a laboratory. The device can be programmed to operate automatically at predefined time intervals.

Some studies:

The analyzer is fairly novel (2017) and is currently being tested by various research institutes around the world. VLIZ is using the analyzer on board of the RV Simon Stevin and in the lab facilities located at the Marine Station Ostend. The measurements support the ICOS and LifeWatch projects.

During the summer of 2017, the system was used by the University of Ghent (Department of Marine Biology) to analyze seawater samples originating from controlled exeriments with marine macrobenthos.

Technical details

Dimensions: 35 x 35 x 50 cm

Weight: 25 kg

Detector: VIS absorption spectrometry

Measuring range: 400 μmol/kg dynamic range, standard range: 2000 μmol/kg to 2400 μmol/kg

Salinity range: 29 - 37 PSU

Temperature of water: 0 - 40 °C

Application area: surface water or stationary

How to borrow the HydroFIA alkalinity system?

Scientists associated with universities or scientific institutions can use our equipment. Contact VLIZ for more information.

Use and conditions

Note: if you use the HydroFIA TA system of VLIZ as a scientist, please refer to it in your publications as follows: "This work was supported by data & infrastructure provided by VLIZ as part of the Flemish contribution to ICOS."


The HydroFIA TA system was funded by ICOS and VLIZ.


Li, Q., Wang, F., Wang, Z. A., Yuan, D., Dai, M., Chen, J., … Hoering, K. a. (2013). Automated spectrophotometric analyzer for rapid single-point titration of seawater total alkalinity. Environmental Science and Technology, 47(Quanlong Li), 11139–11146. http://doi.org/10.1021/es402421a