Unlike foam, matting, or other forms of static filtration media, the Sinking K+ Advanced Media (Black) is designed to move freely within your filter in a downflow filtration system. The constant chaotic movement of the air from your pump causes the media to self-clean. It thus requires no maintenance, the kaldness wagon wheel-styled design, helps to remove ammonia and nitrate in your pond and is designed for use in mechanical/biological filtration systems. Created by Evolution Aqua creators of the the Nexus range of filters. Evolution Aqua adds a range of minerals, magnesium, calcium, enzymes and salt to the raw material used to manufacture K+ Advanced Media. The result means that K+ Advanced Media will mature much faster than many other media types. The media provides the maximum active surface area for the bacteria to colonise, much more than other types of static media. This process removes harmful ammonia and nitrite from the water, this allows the filter to reach optimum effectiveness without the disturbance of periodic cleaning, avoiding unnecessary loss of bacteria within the filter. Specifications Product Gravity Diameter Total Surface Area Protected Surface Area Length K Plus Advanced Media Bio Filter Media (White) Floating 10.5mm 1,350 m² per m³ 1,025 m² per m³ 8mm K Plus Advanced Bio Filter Media (Black) Sinking 10.5mm 1,350 m² per m³ 1,025 m² per m³ 8mm