The project installed a newly developed multi-parameter algal fluorescence sensor (Chelsea Technologies VLux) in the FerryBox system on the ro-ro ferry Finnmaid. Algal fluorescence measurments were taked along the journey through the Baltic sea between Helsinki and Travemunde. The VLux data were compared with several other sensors installed in the FewrryBox system. Further laboratory work was performed to characterise the response of the Chelsea Technologies VLux to various different algal species.