The present invention relates to a seawater purifier comprising the following: a housing having a space therein； a seawater feeding unit which is formed in a pipe shape, with one end penetrating the top surface of the housing and the other end adjacently formed on the bottom surface of the housing, which includes an ozone lamp therein and has one end where the seawater of an aquarium is fed； an ozone lamp unit which has a first air feeding hole formed to feed air； a compartmentalizing plate which compartments the inside of the housing so as to form a space on the bottom surface of the housing and which has a through-hole on the surface thereof, through which the other end of the ozone lamp unit penetrates； a limestone unit which consists of coral sand and shells loaded on the top surface of the compartmentalizing plate in the space of the housing； a zeolite unit which is loaded on the top surface of the limestone unit in the housing space and which fills the housing； a discharging hole which penetrates through the top surface of the housing and discharges seawater passed through the zeolite； an aeration tank unit which has a space formed on one side of the housing； a connecting unit which connects the discharging hole with the bottom of the aeration tank unit； a second air feeding hole which feeds air through one side of the connecting unit； a gas discharging hole which discharges gas through the top of the aeration tank unit； and a seawater discharging hole which discharges seawater through the side surface of the aeration tank unit. The limestone unit and the zeolite unit are mixed at a weight ratio of 1:9.본 발명은 해수 정수기에 관한 것으로, 그 구성은, 내부에 공간이 형성되는 하우징과, 파이프 형상으로 형성되어 일단이 상기 하우징을 상면을 관통하고, 타단이 상기 하우징의 바닥면에 인접하게 형성되며, 내부에 오존램프가 구비되고, 상기 일단에 수족관의 해수가 유입되는 해수유입구와, 공기가 유입되는 제 1공기유입구가 형성되는 오존램프부와, 상기 하우징의 바닥면에 공간이 형성되도록 상기 하우징 내부를 구획하고, 표면에 통공이 형성되며, 상기 오존램프부의 타단이 관통하는 구획판과, 상기 하우징의 공간에서 상기 구획판의 상면에 적재되는 산호사와 패각으로 구성되는 석회부와, 상기 하우징 공간 내부에서 상기 석회부의 상면에 적재되며, 상기 하우징을 채우는
