The invention relates to a photobioreactor for the cultivation of phototrophic organisms, particularly algae, an arrangement of a supporting member in a photobioreactor, as well as to a biogas unit equipped with such a photobioreactor. According to the invention, a transparent pipe system for the flow-through of a culture suspension, in particular algae substrate, is provided. In this case, the transparent pipe system is configured in the form of levels in order to enable a particularly efficient cultivation over several levels.
