Aqueon QuietFlow 10

This filter is best for aquariums 5 gallons and smaller. It is  smaller in size than models 20, 30 and 50. It uses the medium size replacment floss fitler cartidge. It comes with one. While this model 10 is in the 20 gallon aquarium kit from Aqueon, we consider this filter to be best for aquariums 5 gallons and smaller. It is best to use the Model 20 for 10 gallons and larger.