Fluval Prefilter Media (Fluval A-1470) for all Hagen Fluval filtersTop or Middle Media BasketsFor freshwater and marine environmentsFluval Pre-Filter Media consists of chemically inert ceramic rings designed to capture larger solids. Trapping these particles before they can move further through the system, Pre-Filter prevents the clogging of active media that will filter the same water in subsequent stages. This extends the media, and reduces the need for frequent replacement. Pre-Filter is permanent, and requires only occasional rinsing.