The use of renewable biofuels can reduce global carbon dioxide emissions. Fuel production from microalgal biomass is an interesting option. However, microalgae production in so-called photobioreactors (PBR) for the production of goods with low added value is not yet economically competitive to conventional fuel production. Efficient light management can make a significant contribution to improve the economic situation. Within the frame of the present work, an existing photobioreactor (tube reactor, system ecoduna) was equipped with gas sensors for the detection of CO2, O2 and humidity in the exhaust gas. Furthermore, a gas dosing unit has been installed, which allows a quantification of the introduced carbon dioxide. Two cultivation trials of the microalgae species chlorella vulgaris in the photobioreactor (PBR experiments) with records of the cultivation conditions, lasting several weeks, yielded a total harvest of 284,1 g of dried algal biomass and a maximum biomass concentration of 2,04 g/l in the cultivation medium. Based on the results of the photon flux density measurements with the PAR sensor in the laboratory and at the PBR including the literature research, conclusions were made for an optimal light management.