Here a distinction needs to be made, the term nutrient dosing is used for the addition and/or supplementation of the nutrients in the nutrient media sump to maintain the concentration of the essential nutrients in the sump. During the nutrient consumption trials the concentrations of the nutrients in the sump were measured, and their consumption was recorded over time. The term nutrient supply refers to the method of supplying the media over the packed bed. Three nutrient supply methods were tested, namely, continuous trickling at the top, flushing, and flooding. Flushing was defined as trickling at 400 mL/min (flux 10.5 m 3 /m 2 h) for 3 min, a method of a relatively high rate of trickling to wet a larger fraction of the packing. Flooding was the method of filling the whole reactor with the nutrient media till the top of the packing, the nutrient media was completely drained immediately afterward.