Crushed anthracite makes an excellent medium density filtration media. Because of its fractured shape, some of the sediment penetrates deeper into the bed. When compared to equivalent filter sands, this means longer filter runs and less head loss. Backwash rates are also reduced.
Anthracite, because of its unique density, can be used in multi-media filters. At 56 lbs./sq. ft. it will hydraulically lassify and remain above heavier media such as filter sand or Manganese Greensand providing a prefiltration layer.