We aim to determine how well predictions on the growth of algae, based on a theoretical model without needing to know the physiological conditions, would work when tested experimentally. These results predict that partial emptying (retaining a fraction of the algae solution) and filling with fresh medium would improve the production rate of for example Desmodesmus sp. (subspicatus), a species of algae used as a source of biofuel. It was found that the method based on this graphical model is suitable for biological systems when the rate of production is an issue. The application of partial emptying and filling improved production by a factor of 1.28 and 1.26 (at product concentrations 1000 mg/L and 600 mg/L, respectively) when retaining 40% of the algae solution. This method may be particularly useful when large amounts, of biomass are required and to recommend an appropriate retained fraction fot any desired exit concentratioth