Imagine Gold Llc AIM77212 Bio 3 Cartridge Reg 12-Pack Imagine Bio 3 Cartridge Reg 12pk Provides 3 stage filtration in a single cartridge Easy slide in installation in the Imagine Bio System Power Filters and the Tetra/Whisper Power Filters. Imagine Bio 3 Cartridge Reg 12pk Provides 3 stage filtration in a single cartridge Easy slide in installation in the Imagine Bio System Power Filters and the Tetra/Whisper Power Filters Easy slide in installation in the Imagine Bio System Power Filters and the Tetra/Whisper Power Filters