Biological/Mechanical filtration media is available in 1¼" and 2" thicknesses. This material is used in virtually all US manufactured pond skimmers and waterfall units. The open character of this filter media allows for high volumes of water to pass through without clogging while providing optimal surface area to facilitate bacterial colonization. The various densities of this media can be used in sequence or separately for unique filtration requirements. Easily cut, light weight, versatile and durable. Cleaning is fast and easy. This media is weather and chemical resistant.