Fluval U4 Underwater Filter The Fluval U4 Underwater Filter is the largest Fluval U Series internal filter, designed for aquariums up to 65 US gallons / 240 L with powerful 3-stage underwater filtration, adjustable 3-way flow control, and flexible vertical or horizontal placement. High-Capacity U Series Internal Filtration The U4 provides the strongest flow and largest aquarium rating in the U Series, making it a useful primary filter for larger internal-filter setups or a supplemental filter for aquariums that need extra circulation and debris capture. It is ideal where external filtration is not possible, where tubing is undesirable, or where a fully submersible filter is the cleaner choice. Fluval U4 Flow Control and Filtration Features 3-stage filtration combines foam pads, poly/carbon pads, and BIOMAX biological media for complete underwater filtration. 260 US GPH / 1000 LPH pump output provides strong water movement for larger aquariums. Adjustable 3-way flow lets you choose top output, integrated spray bar, or bottom output for different circulation needs. Top output supports maximum circulation and surface agitation for oxygenation. Spray bar output provides gentler even flow that can suit planted aquariums and calmer livestock. Bottom output helps move water lower in the aquarium for deeper agitation and improved circulation patterns. Flip-top lid makes media access fast without removing the entire filter from the aquarium. Versatile positioning allows vertical wall mounting or horizontal placement for shallow tanks and low-water applications. Fluval U4 Underwater Filter Specifications Item number: A480 UPC: 015561104807 Aquarium capacity: up to 65 US gal / 240 L Pump output: 260 US GPH / 1000 LPH Wattage: 12W at 120 V / 60 Hz Dimensions: 13 in L x 4 in W x 4.5 in H / 33 x 10 x 11 cm Filter type: fully submersible internal aquarium filter Filtration stages: mechanical, chemical, and biological Mounting options: vertical or horizontal in compatible aquarium setups Best Uses for the Fluval U4 The U4 is best suited to larger aquariums that need a powerful internal filter with flexible flow output. It can be used as the main filter in compatible aquariums within its rating or as an additional circulation and polishing filter in larger systems where extra in-tank water movement is helpful. Official Fluval U Series Video Setting Up the Fluval U4 Underwater Filter Rinse the included media, install the filter fully submerged in the desired vertical or horizontal position, and select the output direction that best matches the aquarium. Clean foam and poly/carbon media regularly, and rinse biological media in removed aquarium water to help preserve beneficial bacteria. What’s Included Fluval U4 Underwater Filter 2 foam filter pads 2 poly/carbon pads BIOMAX biological media
