A system for separation of a selected component of a biological suspension such as whole blood, plasma, bone marrow aspirate, or adipose tissue, the system comprising: a container having a container top wall and a container bottom wall with a container side wall connecting the container top wall and the container bottom wall to define a container volume; a buoy system moveably positioned within the container, the buoy system having: a first buoy member having a buoy top wall and a buoy bottom wall, the first buoy member defining a first buoy open volume; a selected reactant placed within the first buoy open volume; a first wall passage through the buoy bottom wall of the first buoy member; and a blocking wall (90, 300) adjacent to the buoy bottom wall and configured to be movable relative to the buoy bottom wall between a blocking configuration in which the blocking wall blocks the first wall passage and an open configuration in which the first wall passage is not blocked by the blocking wall; wherein the density of the buoy system relative to the density of the selected component of the biological suspension is arranged to position the selected component in a collection volume adjacent to the buoy bottom wall when a separation force is applied to the container; and, wherein when the blocking wall is in the open configuration, the first wall passage permits the selected component to move between the collection volume and the first buoy open volume to react with the selected reactant within the first buoy open volume. a container having a container top wall and a container bottom wall with a container side wall connecting the container top wall and the container bottom wall to define a container volume; a buoy system moveably positioned within the container, the buoy system having: a first buoy member having a buoy top wall and a buoy bottom wall, the first buoy member defining a first buoy open volume; a selected reactant placed within the first buoy open volume; a first wall passage through the buoy bottom wall of the first buoy member; and a blocking wall (90, 300) adjacent to the buoy bottom wall and configured to be movable relative to the buoy bottom wall between a blocking configuration in which the blocking wall blocks the first wall passage and an open configuration in which the first wall passage is not blocked by the blocking wall; a first buoy member having a buoy top wall and a buoy bottom wall, the first buoy member defining a first buoy open volume; a selected reactant placed within the first buoy open volume; a first wall passage through the buoy bottom wall of the first buoy member; and a blocking wall (90, 300) adjacent to the buoy bottom wall and configured to be movable relative to the buoy bottom wall between a blocking configuration in which the blocking wall blocks the first wall passage and an open configuration in which the first wall passage is not blocked by the blocking wall; wherein the density of the buoy system relative to the density of the selected component of the biological suspension is arranged to position the selected component in a collection volume adjacent to the buoy bottom wall when a separation force is applied to the container; and, wherein when the blocking wall is in the open configuration, the first wall passage permits the selected component to move between the collection volume and the first buoy open volume to react with the selected reactant within the first buoy open volume.