In the present study, the difference in the pH value also caused changes in the total lipid content of both Nannochloropsis sp. and Tetraselmis sp. The similar result also has been observed by Khalil et al. (2010) which indicated that culturing microalgae at an optimal pH can increase the biomass concentration and lipid content. In the combination of all treatments, it was found that Nannochloropsis sp. was the best species to have the highest lipid content when cultured under control condition at 30 ppt and pH 7.5.