Submerged media useful with or without aeration and/or mixing to enhance an aquatic environment by promoting and retaining biogrowth. The media takes the form of a cluster of individual flexible elements having free ends. The media are submerged in a liquid such as a water or wastewater treatment basin or an aquaculture environment. The media are characterized by the ability to promote and retain microbial growth. The media clusters have substantial flow through thicknesses to provide a three dimensional effect along with baffling for increased contact with the liquid being treated. The media may be thin strips constructed to avoid sticking together to allow maximum exposed surface area. The media clusters can create oxic, anoxic and anaerobic environments for maximum treatment during flow through the media cluster. The flexibility of the media elements and their free ends automatically dislodges excessive biomass buildup to avoid clogging of the media.