A bottom coil heat pump type water heater heat pump system is disclosed. The bottom coil heating system for water heating of the basin disclosed in the above is a water tank bottom heating coil disposed at the bottom of the aquarium to warm water in the aquarium； A heat storage tank in which a warm circulating fluid capable of transmitting heat while passing through the warm-up coil of the bottom of the water tank is accommodated； A waste heat pump capable of warming the circulation of the warm circulating fluid between the heat storage tank and the heat storage tank； A waste heat water tank containing wastewater discharged from the aquaculture tank containing waste heat； A warming heat exchanger in which a waste heat circulating circulation fluid between the waste heat pump and the waste heat pump is heat-exchanged with the waste water discharged from the waste heat water tank； And a reverse electrolytic bath capable of back washing the warming heat exchanger. In the warming operation for transferring heat to the aquaculture water tank, the wastewater contained in the waste heat water tank is passed through the warming heat exchanger Circulating fluid circulating between the waste heat pump and the warming heat exchanger is heated so that the circulating fluid is warmed and the circulating fluid heated while passing through the warming heat exchanger passes through the waste heat pump, The heating circulation fluid is warmed by passing through the waste heat pump, and then the warm circulating fluid contained in the heat storage tank is passed through the water tank bottom heating coil Heating the interior of the aquaculture tank, In the backwash operation for backwashing the ventilation, the external washing water electrolyzed while passing through the reverse electrolysis bath is passed through the warming heat exchanger to backwash the warming heat exchanger. According to the disclosed heat pump system for heating the bottom coil heating system, the waste heat i
