Review on Enhanced Adjustable Aquarium Internal Filter with Air Power Aeration System - Ideal for 10-50 Gallon Fish Tanks by Jennifer Wurz

37 gallon tank Freshwater fish: 12 Snails: 5 I would not use this product as a single filter for anything over 20g in an aquarium that has had its water properly treated and replaced. This type of sponge filter is absolutely not designed to remove heavy metals or chemicals from the water. This device does a good job of removing sediment from the water, which contributes to its transparency, but since the sediment remains submerged in the tank, it can still leach toxins. This is a great device to use with a traditional filter and also a great way to add oxygen to your tank. Does not come with air supply valve.