Abstract: An apparatus and method for conditioning water in open fish breeding cages, which can solve the problems of “bloom of harmful seaweed” and the “lack of dissolved oxygen concentration in the water”. The apparatus includes a tube having adjustable open upper and lower ends and an impeller for drawing a major water flow in either direction through the tube. To solve the “bloom of harmful seaweed” the apparatus draws water upward from deeper water with low algae concentration to the bloom zone, dissolving and moving the harmful seaweed far away from the cages. To solve the “lack of dissolved oxygen concentration” the apparatus draws water downward from the surface water having high concentrations of dissolved oxygen to deeper water with low concentrations of dissolved oxygen, increasing the dissolved oxygen concentration in the middle and the bottom of the cages, where the biggest oxygen consuming fish concentration are located.

Abstract: The present invention is directed to an apparatus that extracts the cooler deeper water with the warmer water near the surface in order to reduce the temperature of the upper layers of water within the cage. At the same time, the apparatus produces a water current at the surface that carries the harmful algae away from the set of cages. In addition, the apparatus extracts the oxygen-rich water from the surface and injects it into the deeper water that lacks sufficient oxygen content.