sera BioFibres MediaFor the prefiltration of coarse dirt particles sera biofibres for the biomechanical prefiltration effectively collect coarse dirt particles. Thus, you can protect the following filter media from coarse pollution and increase the biological efficacy of the filter. Suitable for fresh water, marine water and pond water filtration. sera biofibres also serve as an excellent spawning medium and as hiding place for fry. Furthermore, they are ideally suitable