Microalgal SB-222200 density of each genus was analyzed by cell number, biovolumetric composition and proportion. The dominant genus by cell number was Synechococcus sp., with an annual average of 40% ( Supplementary Fig. 2). But, it was less than 5% in proportion by biovolume. Biovolume calculation clearly demonstrated that diversity analysis by cell number didn’t reflect the actual culture condition ( Gamfeldt and Hillebrand, 2011). Dominant genus by biovolume and subsequently biomass concentration was Scenedesmus sp. followed by Microcystis sp. and Chlorella sp. ( Fig. 3 and Supplementary Fig. 3). The difference between the proportion of different genera by cell numbers and biovolume exemplifies the relative importance of biovolume over cell numbers ( Supplementary Figs. 2 and 3). Biovolume represents algal density and species dominance more realistically than cell numbers, as mere counting of number of cells would not reflect different cell sizes between and among species, dependent on life cycle, which largely influence dominance. Hence, biovolume is being used frequently to mimic actual condition in aquatic environments, where density and dominance is often influenced by size rather than numbers ( Gamfeldt and Hillebrand, 2011 and Vanucci et al., 2012). Moreover, dominance of desired species in large algal cultivation systems could only be enhanced by understanding the dominance in that community in actual terms using biovolume calculations ( Park et al., 2013).