Dennerle Bio FilterGranulat is a highly effective biological long-term filter material.+ for effective degradation of harmful substances+ based on natural clay minerals, fired with open-pore finish+ vast colonisation space for biological filtrationMode of use for Dennerle Nano Bio FilterGranulat:Pour Bio FilterGranulat into Nano FilterModule or Filter Extension. Rinse thoroughly with tap water to remove any fine waste which has worn off during transportation. Recommendation: Replace half the quantity of granules every 3 months for maximum performance at all times.