Biological filtration media with biosponge. BIOBALL PLUS. Filtration media for all aquarium filters. For freshwater and marine aquarium. Unique shape and structure with sponge filling provides best environment for nitration bacteria which stops algae growth, stabilize pH level, keeps water clear and clean. BIOBALL PLUS also reduces the concentration of many toxic compounds, including heavy metal ions. It helps to maintain optimal water quality. Before putting BIOBALL PLUS into the filter pls wash them in hot water.