Abstract: A process of growing a phototrophic biomass in a reaction zone, including a reaction mixture that is operative for effecting photosynthesis upon exposure to photosynthetically active light radiation, is provided. The reaction mixture includes phototrophic biomass that is operative for growth within the reaction zone. In one aspect, the carbon dioxide supply is modulated in response to detected process parameters. In another aspect, inputs to the reaction zone are modulated based on changes to the carbon dioxide supply. In another aspect, dilution of the carbon dioxide-comprising supply is effected. In another aspect, pressure of the carbon dioxide-comprising supply is increased. In another aspect, water is condensed from the carbon dioxide-comprising supply and recovered for re-use. In another aspect, the produced phototrophic biomass is harvested at a rate which approximates a predetermined mass growth rate of the phototrophic biomass.