Automatic water changing system for seawater tank

The invention relates to an automatic water changing system for a seawater tank. The automatic water changing system comprises a salt dissolving device, a control unit and a mobile terminal, the salt dissolving device is in communication connection with the control unit, and the control unit is in wireless connection with the mobile terminal; the salt dissolving device comprises a salt dissolving container used for preparing seawater and a material container located above the salt dissolving container, and a salt feeder which is in a big-end-up funnel shape and used for containing sea salt is arranged in the material container. The salt feeder conveys sea salt to the salt dissolving container through a spiral conveyor, the salt dissolving container is provided with an RO water inlet pipeline connected with an RO machine, a salinity meter and a liquid level meter are arranged in the salt dissolving container, a new water pipeline and a waste water discharge pipeline are arranged in the salt dissolving containe