An insulated chilling reservoir for chilling and storing a nutrient solution utilized with a hydroponic system for growing plants. The chilling reservoir has a plurality of exterior walls that enclose an interior chamber that is sized and configured to receive a quantity of the nutrient solution. At least the side exterior walls are insulated. The interior chamber has one or more interior walls and a chamber floor that are in contact with the nutrient solution when it is in the interior chamber. The chilling reservoir has a chilling mechanism associated with the reservoir body and the interior chamber that lowers the temperature of the nutrient solution through the interior walls when the solution is in the interior chamber. A control panel allows the grower to monitor and control the temperature of the nutrient solution. The chilling mechanism includes evaporator coils in the exterior walls, a radiator and a refrigerant system.