Evolution Aqua Nexus 320 (34,000L) Introducing the next generation of Nexus Filtration Systems from Evolution Aqua. Improved Mechanical Filtration Improved Flow Dramatically Improved Clarity Easy To Clean And Maintain Better Solids Handling New & Improved The Nexus 320 and Nexus 220 filtration systems deliver dramatically improved levels of clarity for ponds. Building on the success of the award winning Nexus range this new generation of filters cleverly combine mechanical and biological filtration into one advanced filter system, whilst being incredibly easy to clean and simple to install.