Pond One O2Plus Air Pump MachinePond One O2 Plus 4000, 8000 and 12000 air machines are extremely powerful units. With outputs of 35, 70 and 110 litres per minute these are suitable for seriously large ponds or filters to stimulate aerobic activity or simply to add more oxygen to multiple points around the pond. With the design based upon the Aqua One indoor units, quietness is a given. Outlet size is 1 2 inch. Each unit comes with a 10 gang splitter allowing multiple air stones to