Evolution Aqua Nexus 220 & 320 Lid The Nexus Lids from Evolution Aqua has been designed to perfectly cover the top of the Nexus 220 & 320 and older models. The design of the lid has been developed by experts at Evolution Aqua's head-quarters and combines the very highest quality materials with the brand's undoubtable knowledge within pond equipment manufacture. The Evolution Aqua Nexus Lid is developed from durable plastic for a robust finish and is also UV resistant. The innovative lid keeps light, leaves and other debris from entering the filter to ensure superb running of the Nexus.