Fluval U4 Underwater Filter Style Name:34 to 65 US Gallons                                                                                 |                            Package Type:Standard Packaging   Fluval U4 underwater filter with three stage filtration is ideal for use in fresh, marine or reptile environments. Stage 1 foam removes large particles. In stage 2, the poly/carbon cartridge traps fine debris, improves water clarity and removes impurities. In stage 3, biomax provides optimal biological filtration efficiency.