Abstract: The invention relates to a method for a photochemical process, such as a photocatalytic and/or photosynthetic process, in particular for the culture and production or the hydroculture of microorganisms. A reaction medium (6) is conducted in a meandering manner in a reactor element (2) which is made of at least two upright and connected pipes (3) or chambers (13). Multiple reactor elements (2) are serially connected into a bio solar reactor (1), and a reaction medium (6) flow which is stress-free for the microorganisms is generated in the bio solar reactor (1) using hydrostatic pressure and level compensation. Inlet and outlet openings (4, 5) are arranged on the lower face (8) of each individual reactor element (2) on each of the outermost pipes (3) or chambers (13). The reaction medium (6) flows around all of the connections in the lower region, in particular the inlet opening (4), the outlet opening (5), and the introduction inlet (17).

Abstract: The present invention relates to a photobioreactor 1 for cultivating phototrophic microorganisms, comprising a reactor element 2, which has a tube 3, a maintenance device 4, and a drive system 5, which can move the maintenance device 4 in the tube 3. The photobioreactor is designed such that liquid culture medium 6 containing the microorganisms flows through at least some of the tube 3 when the photobioreactor 1 is in the operating state. The invention is characterised in that the photobioreactor 1 is designed such that the maintenance device 4 can be used in the tube 3 when the photobioreactor 1 is in operating state and can be moved in the tube 3 at least counter to the flow of the culture medium 6 by the drive system 5.