Aquarium overflow system standpipe

An aquarium overflow system comprising a standpipe having an upper end for receiving overflow water above a given level in an aquarium tank, and a lower end for directing the overflow water through a tank wall, an elbow having an elbow outlet mounted to said upper end of said standpipe, and having an elbow inlet, an air vent in said elbow, a set of one or more apertures in said elbow at a level below said air vent, wherein said elbow comprises a first leg extending upwardly from said upper end of said standpipe, and a second leg extending laterally from said first leg and receiving overflow water from said elbow inlet, wherein said one or more apertures are at or below the junction of said first and second legs.