Biological filtration material with bio-sponge. BIOBALL PLUS. Filtration material for all aquarium filters. Designed for freshwater and marine aquariums. Its unique shape and structure with sponge filling provide the best surrounding conditions for nitrifying bacteria, which stop algae growth, stabilize pH levels, and keep the water clean and clear. The BIOBALL PLUS also reduces the concentration of many toxic compounds, including heavy metal ions. It helps maintain optimal water quality. Before placing the BIOBALL PLUS in the filter, rinse it in warm water.