ProFlex models are manufactured using extremely durable materials. The flexibility of each unit allows for three completely different setups: Refugium, Wet/Dry and Berlin. Refugium - Add a refugium light to create a thriving refugium for your reef aquarium. Live rock and certain plants/algae help control excess nutrients that may hinder the growth of corals in the main aquarium. Wet/Dry - Using the BioMedia Accessory Pack, turn the ProFlex into a traditional wet/dry trickle filter. Great for use in freshwater and fish-only saltwater applications to provide advanced biological filtration for a heavy fish load. Berlin - Ideal for reef applications where utilization of a large protein skimmer is imperative. The expansive sump chambers allow for placement of a large protein skimmer and a constant water level.