The Hozelock Pond Air Pump 4500 is a high-performance, reliable air pump suitable for large fish and koi ponds. Adding oxygen into a fishpond is essential for fish health, particularly in densely stocked ponds and in summer months when oxygen levels decline. Air pumps can also be used to circulate water and help prevent the pond from freezing in winter. The Hozelock Pond Air Pump 4500 delivers 4,500 litres per hour with an operating depth of 3m.