Fluval Underwater Filter U4 (130-240L) Dog Tins & Pouches a standard sodium thiosulfate dechlorinator

a standard sodium thiosulfate dechlorinator is not enough

healthy aquarium

Viscoelastic foam-flake filling

on which the smallest model has one and the two larger ones both have two individually adjustable air outlets

overflow:hidden

Fluval Underwater Filter U4 (130-240L) Dog Tins & Pouches a standard sodium thiosulfate dechlorinatorFluval Underwater Filter U3 (90 150L) The Fluval U Series are underwater filters that offers 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. Complete and efficient 3 stage filtration, including BIOMAX biological filtering Ideal for fresh, marine and reptile environments. Now with new and improved design features!