Batch settling and flux theory were used to predict the best working conditions in a continuous flow process for havesting Acutodesmus obliquus using a tannin‐basis flocculant. From batch tests, a settling velocity model was proposed. Three different models were tested: two exponential functions; and one power‐law function. The power‐law function presented a lower variance (1.356 × 10−9) and R2 equal to 0.995. This suggested model was applied in flux theory, and the system performance was predicted by feed flowrate and initial microalgae concentration in continuous flow process. In experimental tests, a pilot settler (0.045 m3) was used to validate the proposed model. Nine different experimental conditions of feed flowrate and initial microalgae concentrations were used to evaluate the settling behaviour of the unit. The flux theory predicted better results when the applied solids flux was near limiting the solids flux. Experimental results showed that in the proposed working condition of 10−5 m3 s−1 feed flowrate and 58 kg · m−3 initial microalgae concentration, the highest biomass removal was 98.3 %, and sludge concentration profiles could stabilize over time. Overall, these results demonstrate a potential application of the batch tests and theory flux to predict a continuous flow process, considering biomass purification.