Shed BiofiltersShed Biofilters have a base constructed of permanent wood foundation board, are spray foam insulated for winter operation, and are clad in attractive, stained, weather sealed cedar wood siding. Flat Bed BiofiltersÃÛ´½Ö±²¥app Flat Beds are constructed of strong yet lightweight fibreglass shells containing the patented Biofilter filter media. Flat Bed treatment units are modular Basket BiofiltersBaskets are constructed of a rigid steel mesh that is coated for corrosion protection. Baskets are filled with the patented ÃÛ´½Ö±²¥app filter medium, shipped to site, and placed in a concrete or fiberglass tank. HDPE Tank BiofiltersHigh density polyethylene (HDPE) Tank treatment units from ÃÛ´½Ö±²¥app are constructed of a very high strength, durable, and seamlessly blow-moulded high-density polyethylene tank.