Patent ID: 7264714

Claim:
A protein skimmer for use in purification of water used by culture of fish or other water organisms in a reservoir, aquarium, or tank ( 2 ) having a circulation system comprising one or more discharge tubes ( 4 ) from the reservoir ( 2 ) to a pump ( 5 ) for circulation of water, and a return tube ( 3 ) for water directly or indirectly from the pump ( 5 ) to the reservoir ( 2 ), wherein the return tube ( 3 ) comprises a generally horizontal, straight portion ( 90 ) with at least one upwardly directed side branch ( 9 ) which has an aperture ( 91 ) to air, in which the generally horizontal straight portion ( 90 ) is arranged for rapid passage of the water past the side branch ( 9 ) and to have the water level at or above the intersection of the side branch ( 9 ) and the straight portion ( 90 ), and the side branch ( 9 ) is directed rearward relative to the direction of the water flow in the straight portion ( 90 ), so that during water flow a protein foam will be formed at the water surface at the intersection of the side branch ( 9 ) with the straight portion ( 90 ) of the return tube ( 3 ), and that the protein foam is allowed to grow from the water surface for the discharge through the side branch ( 9 ), and in which the return tube ( 3 ) further is arranged to for having the entirely or partially purified water to flow further through the straight portion ( 90 ) and directly or indirectly to the reservoir ( 2 ).