The Fluval fine pre-filter cartridge for the Fluval G Series is designed for daily use with marine aquariums where suspended debris is minimal or it can be used as a polishing cartridge for standard or fresh water aquariums. The fine mesh will trap debris 75m or larger for unparalleled mechanical filtering results. Designed as a no bypass system, debris remains caught between each pleat until it is removed and rinsed. However, solid wastes can break down into soluble wastes and regular cartridge rinsing is recommended.+ Fine Pre Filter Cartridge for Fluval G3, Fluval No.: A417+ Fine Pre Filter Cartridge for Fluval G6, Fluval No.: A418