Originally Posted by Aluyasha
I have noticed on a few fish tank boxes that they call the air bubbler thing a filter. Is it really a filter or are they lying to get you to buy it?
And if I had a 3 gallon with a air bubbler thing, how often would I need to change the water?
Well, it depends, things like sponge filters are just bubblers inside a sponge. They work because water is drawn through the sponge as the air bubbles up from inside of it, or something like that. So, if there's even some small filter media along with the bubbler, techincally one could call it that. If you cycle the tank with that and have enough media to grow good bacteria, then only once a week should be fine...