FLUVAL U4 INTERNAL FILTERU4 Underwater Filter, up to 65 US Gal 240 L Offering outstanding 3 stage filtration, increased water movement and vital aeration, Fluval U Series internal filters are the perfect solution where external filtration is not possible. Features Designed for aquariums up to 65 US Gal 110 L 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,