Fluval "U" Underwater Filter. Fluval underwater filters with three stage filtration are ideal for use in fresh, marine or reptile environments. Stage 1 foam removes large particles. Stage 2 poly/carbon cartridge traps fine debris, improves water clarity and removes impurities. Stage 3 BIOMAX provides optimal biological filtration efficiency. For aquariums, terrariums and turtle tanks Ideal supplemental or stand-alone filter, or for installations where external filtration is not possible New Sleek Design New Easy Grip Water Control Paddle New Redesigned Media Cartridge – Traps more debris Use as a primary filter for smaller aquariums, or supplementary filter for larger aquariums Position horizontally for shallow tanks, larger tanks with low water levels, or to create a decorative waterfall feature Position vertically against aquarium wall to create currents or customized flow patterns Convenient flip-top lid allows for quick and easy access to filter cartridge for maintenance or replacement Made in Italy Ideal for freshwater, saltwater and reptile environments Available in the following models: Fluval U1 Includes adjustable flow control and comes complete with 1 foam pad Suitable for aquariums up to 55 L (15 US gal) Output :250 L(65 US gal.) Fluval U2 Adjustable 3-way flow control – Top Output for circulation and oxygenation, Integrated Spray Bar for a gentle even flow, and Bottom Output for deepwater agitation Comes with 2 Foam Pads, 2 Poly/Carbon Cartridges, and BioMax Biological Rings Suitable for aquariums from 45 to 110 L (12 to 30 US gal) Output :400 L(105 US gal.) Fluval U3 Adjustable 3-way flow control – Top Output for circulation and oxygenation, Integrated Spray Bar for a gentle even flow, and Bottom Output for deepwater agitation Comes with 2 Foam Pads, 2 Poly/Carbon Cartridges, and BioMax Biological Rings Suitable for aquariums from 90 to 150 L (24 to 40 US gal) Output :600 L(155 US gal.) Fluval U4 Adjustable 3-way flow control – Top Output for circulation and oxygenation, Integrated Spray Bar for a gentle even flow, and Bottom Output for deepwater agitation Comes with 2 Foam Pads, 2 Poly/Carbon Cartridges, and BioMax Biological Rings Suitable for aquariums from 130 to 240 L (36 to 65 US gal) Output :1000 L(260 US gal.)