Penn-Plax Undergravel Aquarium Filter for 20 (Long) - 29 Gallon Tanks – Two 14” x 11.1” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks

NOTHING LIKE OLD SCHOOL: The Clear-Free Premium Under Gravel Filter is air driven and utilizes an Air Pump (not included) to cycle crystal clear water throughout your aquarium, while keeping a crisp and neat look inside. This means there’s less “moving parts,” making for simplistic and easy maintenance. This filter is suitable for most 20 (long) – 29 gallon aquariums.. BIOLOGICAL, CHEMICAL, AND PHYSICAL FILTRATION: As air is pushed through the Air Stones and rises through the Lift Tubes, water is gently suctioned through gravel and the filter plates, allowing both air and water to pass through the Filt-a-Carb Activated Carbon Cartridges. When water continues to be drawn through, anaerobic bacteria collects and colonizes within the gravel and filter plates.. ALSO AERATES YOUR TANK: Since the Clear-Free Premium Under Gravel Filter is air driven through the use of Air Stones and an Air Pump (not included), it also aerates your tank. In essence, your aquarium is being filtered and aerated at the same time, though the same system. It’s a filter and bubbler in 1.. ITEMS INCLUDED: The Clear-Free Premium Under Gravel Filter includes 2 Filter Plates, 2 Adjustable Lift Tubes, 2 Straight Airline Tubes, 3 Filter Plate Connecters, and 2 Replaceable Filt-a-Carb Activated Carbon Media Cartridges.. MEASUREMENTS: Each Filter Plate Separately = 14” (W) x 11.1” (D) / Filter Plates Together = 28” (W) x 11.1” (D) / Each Lift Tube at Filter Plate Base = 13” – 16”