Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks – Four 11.25” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks (CFU55)

This under gravel filter system is designed with plastic filter plates to sit under the gravel in your aquarium tank, allowing water to flow freely through while collecting bacteria and debris. An air pump and air tubing are necessary to ensure that the filter works perfectly. The size of your tank will determine the size of the air pump you need. While there are no videos available yet, you can assemble this filter system easily and quickly, with review feedback noting it taking 1 hour to install. There is one minor issue in that it can be a little larger and has a gap of 2 inches in a 55-gallon tank. In terms of filtration, it's not necessary as a good air pump suffices. You can reuse the activated carbon filters several times by flushing and cleaning with chlorine remover. Weekly vacuuming of the gravel and changing a fraction of tank water should be sufficient. Review feedback has been generally positive with most customers happy with their purchase.