CellDeg's High Density Cultivation system allows for efficient accumulation of biomass of photosynthetic organisms, such as cyanobacteria and microalgae. The media requires a higher nutrient concentration, to facilitate high growth rates over extended periods. This protocol describes the media composition used in the Lindberg lab at Ångström laboratory (Uppsala University). The basic composition was previously described in Lippi et al., [1], and has been slightly modified:different iron source usedNaNO3 as sole (major) nitrogen source (no additional KNO3)no cobalt is added to the standard media no copper is added to the standard media[1] Lippi L, Bähr L, Wüstenberg A, Wilde A, Steuer R: Exploring the potential of high-density cultivation of cyanobacteria for the production of cyanophycin. Algal Research 2018, 31:363-366