Blue Stone Pump, 900 GPH (eco-4750) Blue Stone Pump Blue Stone Pump - A 900 GPH; fully submersible, or inline, magnetic drive pump offered only by General Hydroponics. Used with the popular AeroFlo2 30 and 36 units, the BlueStone pump comes with a sponge pre-filter and 1/2" fittings. Because it has only one moving part, the pump does not require the use of bothersome seals. Manufacturer's Product Information MSRP $ 109.98