The presence of algae in surface waters is a potential threat to the quality and ecology of the water system. The control and monitoring of the algae concentrations are therefore of high importance. The ALGcontrol offers on-line monitoring of different kind of algae through fluometric a (fluorescence) technique. Fluorescence is the property of some atoms and molecules to absorb light at a particular wavelength and to subsequently emit light after a brief interval. Algae possess this property. With this technique it is possible to identify different kind of algae by converting multiple fluorescent values into chlorophyll concentrations.