Sera Siporax Professional 15 mm 10 l, 6.4 lb. Aquarium Filter Accessories Maximum optimization of biological filtration Can colonise aerobic and anaerobic bacteria Three-dimensional pore structure, excellent for settling of filter bacteria Made in Germany For all filters in freshwater and marine aquariums as well as ponds All glass biological filter medium Available for fresh- and saltwater aquariums as well as garden ponds Harbors aerobic and anaearobic bacteria Three dimensional pore structure Innovative high quality mechanical filter media Filters even finest particles, such as sludge and floating algae For crystal clear water within 24 hours Reusable