Models have been formulated and analyzed for photosynthesis by algae in turbulent, channel flow. Analytical and computational for results for different stochastic, kinematic models of algal motion have been obtained for two different rate mechanisms. The results indicate that turbulent mixing can achieve an increase in the rates and efficiencies of photosynthesis by realizing the intermittency effects. Optimum levels of turbulence are shown to exist in turbulent channel flow for the mass cultivation of algae. The methodology of this paper is relevant to photochemical reactions in general.