Sera Biofibres Coarse 40 g E

Filter fibre for pre-filtration, in a 40 gram pack. Coarse is the coarser of the two grades, and it is also available in a 400 gram pack.

What it does in the filter: biofibres collect coarse dirt biomechanically before the following media. That keeps the biological media clean and stops their performance dropping. The fibre is suitable for fresh water, marine water and pond filtration.

Two other uses: the manufacturer also names the fibre as a spawning medium and a hiding place for fry. It is used in shrimp transport as well: in a transport bag the fibre gives the animals something to hold on to, which makes the journey less stressful for them.