Control of biological contamination. A. Chemicals (red arrows) are released into the culture medium in order to combat biological contamination (orange) in an open system containing microalgae (green).The circle represents the blades turning at low speed for system circulation. B. Controlled management of allelopathy-derived compounds (magenta) from microalgae (green) eliminating biological contamination in open-pond cultivation. The circle represents the blades rotating at low speed for system circulation.