ENPRESS ONE Water Filtration Simplified Blue Series carbon block filters for Cartridge Tank are POE filtration solutions flowing up to 15 gpm and treating 250,000-plus gallons of water. Imagine … no more control valve, drain, wasted backwash water or dumping of carbon during re-bedding. This is the easy-to-remove cartridge filtration solution of the future. The Blue Series is 100 percent non-metallic, NSF 44 & 61 listed and made in the U.S.