NOVELTY - A closed system bioreactor system comprises flexible tube(s) containing an aqueous medium (102); a thermal barrier (124) dividing the tube into an upper chamber (126) and a lower chamber (128), to regulate the temperature of the medium; a first control housing (108) coupled to one end of the tube and configured to circulate the medium to or from upper chamber and to or from lower chamber; and a flow control mechanism in mechanical association with the control housing, to alternatively direct to the medium to upper or lower chamber to thermally isolate/expose the medium to the environment.    USE - As closed system bioreactor system for growing and harvesting a variety of aquatic organisms, including algae; and for producing as biodiesel, methane, animal or human food, precursors for polymer production or other chemical products.    ADVANTAGE - The closed system bioreactor system can be installed and operated in an outdoor environment where it is exposed to environmental light, temperature and weather. The bioreactor provides improved thermal regulation and maintains temperature within the range compatible with optimal productivity of aquatic organisms. The bioreactor system provides improved capture of oxygen produced by the aquatic organisms and improved performance of the apparatus to efficiently keep aqueous material, and hence the aquatic organisms, where they are desired. In this way the apparatus also reduces problems from competing organisms, predatory organisms, pathogenic organisms and/or other extraneous species. The closed system bioreactor apparatus is scalable to any level of production desired, from a small backyard operation to one covering square miles of surface. The bioreactor technology stabilizes aquaculture medium temperature with low energy usage, practical on any scale. The closed system bioreactor system supports large scale and low cost cultivation and harvesting of aquatic organisms. The system economically supports the massive cultivation and harvesting of aquatic organisms, such as algae.    DETAILED DESCRIPTION - A closed system bioreactor system comprises at least one flexible tube capable of containing an aqueous medium (102), and having a first open end and a second open end; a thermal barrier (124) within the flexible tube to regulate the temperature of the aqueous medium, where the thermal barrier divides the flexible tube into an upper chamber (126) above the thermal barrier and a lower chamber (128) below the thermal barrier, where the medium may be alternatively directed to the upper chamber or the lower chamber to thermally isolate or thermally expose the aqueous medium to the environment; a first control housing (108) coupled to the first open end of the at least one flexible tube and configured to circulate the aqueous medium to or from the upper chamber of the at least one flexible tube and to or from the lower chamber of the at least one flexible tube; and a flow control mechanism in mechanical association with the first control housing to direct the medium above or below the thermal barrier of the at least one flexible tube. The flow control mechanism comprises a septum clamp connected to the first end of the thermal barrier; at least one actuator connected to the septum clamp and operable to move the septum clamp between an up position to facilitate a flow of the aqueous medium below the septum clamp and the thermal barrier and thus between the control housing and the lower chamber of the tube, or a down position to facilitate the flow of the aqueous medium above the septum clamp and the thermal barrier and thus between the control housing and the upper chamber of the tube; an upper valve member connected to the septum clamp for restricting the flow of the aqueous medium into the upper chamber of the tube when the septum clamp is in the up position but permitting a flow of the aqueous medium out of the upper chamber of the tube when the septum clamp is in the up position; and a lower valve member connected to the septum clamp for restricting the flow of the aqueous medium into the lower chamber of the tube when the septum clamp is in the down position but permitting a flow of the aqueous medium out of the lower chamber of the tube when the septum clamp is in the down position. The system further comprises at least one peristaltic roller coupled to the flexible tube to circulate the aqueous medium through the flexible tube and to remove gas bubbles from the flexible tube. The aqueous medium contains at least one aquatic organism. The thermal barrier comprises a polyethylene substrate; and thermally insulative members. The thermally insulative members comprise a polyester substrate and a foamed polyethylene insulative layer adhered to the polyester substrate. An INDEPENDENT CLAIM is included for a method for cleaning the flexible tubes, involving providing the bioreactor; moving the first peristaltic roller to a position on the first section of flexible tube distal the first control housing; moving the second peristaltic roller to a position on the second section of flexible tube distal the first control housing; and simultaneously moving the first peristaltic roller and the second peristaltic roller towards the first control housing to create an increased aqueous medium pressure in the portion of the aqueous medium chamber between the peristaltic rollers, where the increased pressure causes increased interior surface scrubbing of the first and second sections of flexible tube and increased particle re-suspension of the aquatic organisms within the first and second sections of flexible tubes.    DESCRIPTION OF DRAWING(S) - The figures show a side cross sectional view of a closed system bioreactor apparatus, and a cross sectional side view of part of the closed system bioreactor apparatus.    Aqueous medium (102)    Rollers (106)    Control housings (108, 110)    Thermal barrier (124)    Upper chamber (126)    Lower chamber. (128)