Macro Aqua AWN-40 Medium Internal Dry Protein Skimmer Filter, 660gph, Up to 396gal Tank Size: 5.9in. x 5.9in. x 22in (15cm x 15cm x 56cm) Water Flow Rate: 660GPH (2500LPH). The water outlet which is designed as water lock, can produce very stable water flow, without much water fluctuation. The skimmer has an integral body made of impact resistant material. Easy to handle and operates with high efficiency and safety. The 4 rubber pads underneath reduces noise and achieves quiet operation. The cone body together with the special flow guiding holes can centralize bubbles.