Neptune Systems COR-20 Intelligent Return Pump (2000 GPH)Use With or Without an Apex Controller! The intelligent Neptune COR 20 Return Pump is easily the smartest pump available. Directly connect to any Apex controller through an Aquabus Port, but if you do not have a controller, don't worry, you don't need one! The COR 20 is capable of stand alone operation, but also offers advanced control features that can be found by using the Apex Fusion Cloud Software (Apex required). Add a COR pump to your system