Specially designed sintered glass medium, with an enormous surface area of 18,300 sq. ft. per U.S. gallon. This highly-porous rock material promotes biological water purification and eliminates toxic ammonia and nitrite. For saltwater and freshwater use. Suitable for all EHEIM external filters. One liter equivalent to 2 lbs.; two liter equivalent to 4 lbs.
When changing filter material, mix 1/3 of the used medium with new medium to achieve rapid repopulation of bacteria. Substrate may be washed with lukewarm water and be used several times. Before initial use, rinse thoroughly.