Fully weatherproof outdoor electric air pump for small ponds. This pond air pump from this top aquatic brand is the perfect addition for small ponds. Adding oxygen into a fishpond is very important for fish health, particularly in densely stocked ponds and in the summer months when oxygen levels decline. Air pumps can also be used to circulate water and help prevent the pond from freezing in winter. This pump provides enough for oxygen for a pond with a volume of roughly 4,600 litres (3,600 if keeping fish and 1,800 if keeping koi).