An air pump propelled aquarium cleaner to be disposed within an aquarium filled with water and connected to an air pump, such that the air pump propelled aquarium cleaner is propelled by air to move and to clean a bottom of the aquarium.

An automated underwater sensor cleaning device according to one embodiment of the present invention includes a sensor protection tube, a movable cleaner that is installed on the sensor protection tube and cleans the sensor protection tube while vertically moving along the sensor protection tube, and a controller configured to control an operation of the movable cleaner.

An automated underwater sensor cleaning device according to one embodiment of the present invention includes a sensor protection tube, a movable cleaner that is installed on the sensor protection tube and cleans the sensor protection tube while vertically moving along the sensor protection tube, and a controller configured to control an operation of the movable cleaner.

A plant for aquaculture, for farming of fish or other aquatic species, comprising a closed or semi-closed tank, at least one inlet for water to the tank and an outlet for water from the tank. The plant is distinguished in that the outlet comprises two pipes, wherein an outer pipe is arranged outside an inner pipe, the outer pipe extends from a bottom of the tank up to an outer pipe upper end, and the outer pipe comprises openings distributed along the immersed part of the outer pipe, the inner pipe extends from the bottom of the tank up to an inner pipe upper end, and the inner pipe comprises an outlet opening at the inner pipe upper end and/or outlet openings at elevation below the inner pipe upper end, and a main outlet from the tank is arranged in the tank bottom in position inside the inner pipe.

A plant for aquaculture, for farming of fish or other aquatic species, comprising a closed or semi-closed tank, at least one inlet for water to the tank and an outlet for water from the tank. The plant is distinguished in that the outlet comprises two pipes, wherein an outer pipe is arranged outside an inner pipe, the outer pipe extends from a bottom of the tank up to an outer pipe upper end, and the outer pipe comprises openings distributed along the immersed part of the outer pipe, the inner pipe extends from the bottom of the tank up to an inner pipe upper end, and the inner pipe comprises an outlet opening at the inner pipe upper end and/or outlet openings at elevation below the inner pipe upper end, and a main outlet from the tank is arranged in the tank bottom in position inside the inner pipe.

An aquaculture system, such as a fish or shrimp farming system, is provided and based on recirculation aquaculture, the system comprising: at least two farming tanks 105e; at least one tank-specific water treatment unit (106d, 107h) that is connected to one of the tanks and configured to treat water of said tank; at least one shared water treatment unit (108, 109) that is connected to all of the tanks and configured to treat water that is recirculating in the system; and a means 101a for recirculating water in the system.

An aquaculture system, such as a fish or shrimp farming system, is provided and based on recirculation aquaculture, the system comprising: at least two farming tanks 105e; at least one tank-specific water treatment unit (106d, 107h) that is connected to one of the tanks and configured to treat water of said tank; at least one shared water treatment unit (108, 109) that is connected to all of the tanks and configured to treat water that is recirculating in the system; and a means 101a for recirculating water in the system.