Fluval Edge Pre-Filter Sponge. Specifically designed for the Fluval EDGE power filter, this pre-filter sponge effectively collects fine debris and keeps your aquarium clean. Easy to install over the filter intake, the sponge also prevents small or baby fish from being sucked into the filter. Key Features : Specifically designed for Fluval EDGE power filter Effectively collects fine debris and keeps your aquarium clean Easy to install over the filter intake Also prevents small or baby fish from being sucked into the filter.