Gardena Water Pumps - Pump Preliminary Filter Flow rate up to 6,000 l/h - Gardena 1730-20 Ref: GRD1730 Flow rate up to 6, 000 l/h. Protects the pump (Garden Pumps, Pressure Tank Units, Petrol-driven Motor Pumps) from dirt. With washable filter. Recommended in particular for pumping sandy media. With 33.3 mm (G 1) mating thread. £36.99