Tetra Bio Filter BF Replacement Foam for External Filters EX400/600/700,  EX1200

Use of Tetra BF replacement Foam in Tetra External Filters EX ensures that the aquarium water is filtered effectively. Biologically active bacterial cultures that transform harmful nitrite into the plant fertiliser nitrate settle in the filter foam. The foam structure also carries out physical filtration, removing visible particles from the aquarium filter