API is excited to introduce the Nexx FILTER! Nexx is an Evolution in Filtration and designed with you in mind. A modular filter that grows with your needs; you have the ability to add EXTENSIONS to the FILTER in order to increase filtration capabilities. The Nexx FILTER delivers crystal clear water quality for your aquarium by using the Size 4 Bio-Chem Zorb cartridge. Superior filtration with no bypass. Ultimate convenience with 4 minute or less media changes, no mess and filtration options give you the filtration and flexibility you want. - No priming - Quick and easy 3 steps to media replacement in 4 minutes or less - Flexible filtration options - Superior water quality with the proven results of Bio-Chem Zorb Size 4 cartridge