A system for exchanging water for farming used in a factory aquafarm in accordance with an embodiment of the present invention, with respect to a biofloc type factory aquafarm having a plurality of farming tanks, comprises: farming tanks prepared in the shape of a cylinder； farm water suction ports formed in the side wall of the farming tanks and spaced from the bottom surface of the farming tanks by a height (h1) lower than 50% of a depth of the farming tanks； a precipitation tank receiving water for farming from the farming tanks and primarily settling the water for farming； a filtration tank receiving the relatively clean water in an upper part of the precipitation tank due to the precipitation of residual products and secondarily settling the water for farming； a first channel having one end connected to the farm water suction ports and the other end connected to the precipitation tank so as to supply the water for farming in the farm tanks to the precipitation tank； a second channel having one end connected to the precipitation tank and the other end connected to the filtration tank so as to supply the water for farming, of which the residual products has been primarily settled in the precipitation tank, to the filtration tank； and a third channel having one end arranged in water adjacent to the surface of the water in the filtration tank and the other end arranged in the upper part of the farming tanks from which the water for farming is blown down so as to supply the filtered water for farming to the farming tanks.본 실시예에 따른 공장형 양식장의 양식용수 교환 시스템은 복수 개의 양식수조를 가지는 바이오플락 방식의 공장형 양식장에 있어서, 원통형상으로 마련되는 양식수조； 상기 양식수조 측벽에 형성되며, 상기 양식수조의 깊이의 50%미만의 높이(h1)만큼 양식수조의 바닥면에서 이격되는 양식용수 흡입포트； 상기 양식수조의 양식용수를 공급 받아, 1차적으로 양식용수를 침전시키는 침전수조； 상기 침전수조에서 부산물이 침전되어 상측에 떠오르는 상대적으로 깨끗한 양식용수를 공급 받아 2차적으로 양식용수를 침전시키는 여과수조； 일단은 상기 양식용수 흡입포트와 연결되고, 타단은 상기 침전수조에 연결되어 상기 양식수조의 양식용수를 상기 침전수조로 공급하는 제 1 유로； 일단은 상기 침전수조와 연결되고, 타단은 상기 여과수조와 연결되어, 상기 침전수조에서 1차로 부산물이 침전된 양식용수를 상기 여과수조로 공급하는 제 2 유로；
