The invention discloses a bioreactor that creates a rotating or circulating water stream in an enclosure. It is able to both remove undesired chemicals and protein scum. The water is brought into the bioreactor by a pump and diverted into the body of the bioreactor. From there it rises through the biosubstrate and falls into a central pipe where it enters branch pipes and exits at a non-perpendicular angle to the bioreactor. This generates a rotation or circular currents of the water. The invention can be used a part of a fish pen system. The water current aid in sediment removal and keeps the fish more active； as they fight the current. Methods and uses of the bioreactor are also disclosed.The invention discloses a bioreactor that creates a rotating or circulating water stream in an enclosure. It is able to botn remove undesired chemicals and protein scum. The water is brought into the bioreactor by a pump and diverted into the body of the bioreactor. From there it rises through the biosubstrate and falls into a central pipe where it enters branch pipes and exits at a non-perpendicular angle to the bioreactor. This generates a rotation or circular currents of the water. The invention can be used a part of a fish pen system. The water current aid in sediment removal and keeps the fish more active； as they fight the current. Methods and uses of the bioreactor are also disclosed.
