Bench-scale, batch experiments were conducted to elucidate carbon and nutrient dynamics in the full-scale mix tank and PBRs. Duplicate batch experiments were conducted in cylindrical, bench- scale PBRs constructed from clear cast acrylic with the same diameter as the full-scale system (102 mm i.d., 91 cm height, 7 L working volume). The bench-scale PBRs were placed in the greenhouse with the full-scale PBRs to match light and temperature conditions. A third PBR (102 mm i.d., 69 cm height, 5 L working volume) was run in parallel, without being sampled, to ensure sufficient solids for the subsequent mix tank bench-scale experiment. Bench-scale mix tank experiments were conducted in duplicate under dark conditions in opaque, HDPE plastic containers (4 L working volume) with lids.