Hozelock 640 Pond Air Pump - 1805Adding 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. Key Features: 640 lph Maximum depth 1. 2m Includes 10m Tube, 4 Air Stones & 4 Non Return Valves