Hydrocyclones are used for separation where greater efficiency is required than what is achievable with swim-sink tanks. These units work with a pressure force from a feeding pump and reach a higher separation effect (20x gravity) by using the rotational forces of moving water. The PE/PP material leaves the Hydrocyclone at the upper end with the mainstream of water. PET exits at the lower end with only small amounts of water. By choosing nozzle sizes at the outlets of the cyclone the selectivity can be adjusted. Additional equipment required to complete a hydrocyclone circuit include a mixing tank (turbo washer) and a feeding hydro.