Experiments were conducted to test algae growth in reused growth medium, simulating water reuse in large-scale algae cultivation for biofuels and bioproducts. The non-axenic marine microalgae Chlorella sp. D046, Navicula sp. SFP, and Staurosira sp. C323 were each grown in medium previously used to grow Staurosira sp. C323. Media were filtered (0.2 µm) and amended with nutrients prior to reuse. The bacteria community, or algal microbiome, was identified in the inoculum algae cultures and in final experimental cultures. The project goal was to determine if specific bacteria taxa become depleted or enriched in reused medium cultures, compared to cultures in fresh growth medium, which could be helpful in designing algae cultivation and water reuse strategies.