Review on Lee's Pet Products Undergravel Fishbowl Filter, 2-Gallon - ALE13202 by Javon Kulik

I live under gravel pack and this was just what I needed for my 3.5 gallon betta aquarium. (It might be a bit small for my aquarium, but I've never seen a larger version of this design). The filtration that came with the tank covered most of the tank and this system allows me to see everything. As others have said: the plastic decor is too harsh for fish with thin fins, and you'll need replacement filter media (I use a combination of activated carbon and zeolite to prevent ammonia bursts that can suddenly occur in smaller aquariums). I plan to change the duct connection a bit so I can insert an air stone from the bottom of the bubbler tube for smaller air bubbles and (hopefully) a quieter sound. It can gurgle quite a bit. However, this is a great design for small bowls and round tanks.