API nexx Aquarium FILTERAPI nexx Aquarium FILTER is designed with you in mind. A modular external filter that grows with your needs and delivers great water quality for your aquarium. Ultimate convenience, no mess, quick filtration media changes and filtration options that give you the flexibility you need and want. Easy water changes with no priming and no disconnect. The nexx Aquarium FILTER provides crystal clear water that flows through the resin cartridges - not over the top bypassing the media. The modular system has an easy clip connect to add extensions for added filtration or larger aquariums (API nexx Aquarium EXTENSION Filter sold separately).