A photobioreactor system may include a one or more fluidly connectable tubes for growing or producing microorganisms or biomass such as microalgae. The system may include either a single tube loop or an array of tubes. A first fluid may be held in the tube or tubes, and an inlet port may be provided for introducing a second fluid into the tube or tubes. The tube or tubes may be arranged vertically so that the second fluid rises through the tube or tubes. An outlet port may be provided at the top of the tube or tubes to remove the second fluid. The second fluid may be recirculated through the system via inlet and outlet lines as well as a pump and a replaceable reservoir for holding the second fluid. Where there is an array of tubes, a single inlet and outlet line may be sued for each tube.
