The Overflow System by All-Glass Aquarium is engineered to allow maximum water flow to the main filter system, while greatly reducing the cascading water sound. The  Overflow System design draws water from the surface, mid-range, and bottom levels of your aquarium. This provides more effective circulation and filtration, which in turn helps eliminate dead water zones in your aquarium. The Overflow allows more water flow than the previous All-Glass overflow design and significantly outperforms the competitors tube design. The new design can handle an actual maximum flow through rate of 600 G.P.H. per overflow. The Overflow is securely bonded and sealed to the back wall of the aquarium with silicone. The overflow construction makes it rugged and durable and allows the user to stack rock or other decorating materials right up against it…no unprotected flimsy clear plastic tubes to worry about. This new back wall mounted design also keeps unsightly plumbing from being seen. Aquariums up to 110 gallons are fitted with one Overflow and are rated for a maximum flow through of 600 G.P.H. (Using a rated 2,400 G.P.H. pump at a 5 foot head).