Ocean Free Square Cata-Pure Cartridge for Hydra 20/30/40/50 (4pk) The Cata-Pure Cartridge can last 9-12 months depending on the amount of fish and is functional in marine environments. Fits all model Hydra Internal Filters, Hydra Filtron &...

Ocean Free Square Cata-Pure Cartridge for Hydra 20/30/40/50 (1pk) The Cata-Pure Cartridge can last 9-12 months depending on the amount of fish and is functional in marine environments. Fits all model Hydra Internal Filters, Hydra Filtron &...

Ocean Free Hydra 40 Impeller Shaft Replacement Impeller Shaft for Ocean Free Hydra 40 Internal Filter Impeller sold separately.

Ocean Free Hydra 40 Impeller Replacement Impeller Shaft Ocean Free Hydra 40 Internal Filter

Ocean Free Hydra 40 Superior Bio Foam Replacement Superior Bio Foam for the Hydra 40 Internal filters.