Lily Pipe Set consists of 2 major parts: the inflow and outflow pipe. These pipes are used to increase water movement in lower parts of the aquarium where water can easily become stagnant and at the same time aerates and skims away accumulation of oil at the water surface with a simple attachment of a water skimming device on its inflow pipe. Powerful flowrate is used to create strong currents. The feature of the outflow pipe is to create powerful flowrate for stronger currents without disturbing the aquascape within the aquarium. These are great for the flora and fauna that prefer high flowing currents. Despite the strong flow being created a powerful flowrate is still suitable for both growth of aquatic plants as well as coral reef. Total Pipe length: 36.5cm. Surface skimmer diameter: 4cm. Surface Skimmer housing: 20cm. Strainer diameter: 2.2cm. U Pipe Spacing: 5cm. Outlet depth: 10cm Outlet diameter: 1.2cm. Lily pipe holder included.