Filter cartridge for Tetra Easy Crystal FilterBox 600 for crystal clear healthy water thanks to innovative filter cartridge: fast clean replacement dry hands! Ensures crystal clear healthy water with its intensive mechanical biological and chemical filtration. Mechanical and biological Filtration: the double-layered Filter Floss Pads with a large surface area reliably remove even the tiniest particle. White side = coarse pre-filter; beige side = fine filte. rNo need to rinse filter medium no more wet hands. With Timestrip: indicates when the filter cartridge needs to be replaced.