I just realized that the aquarium I have doesn't have a true filter. It said it had an undergravel filter but it has an air pump with an airstone. Here is a link to what I have:
This is what it looks like set up...not my picture. I haven't uploaded any yet. But you can see what the air tube thing looks like in the tank:
Luke seems to like the bubbles, though I did have to put a gang valve on it to restrict the flow. But I don't know how I'll tell if he blows a bubble nest.
I've read conflicting things about 2.5 gallon tanks and needing a filter. I plan to do a 25-50% water change about twice a week (from what I've read here). So what kind of filter do I need and if I get one, do I then remove the air pump? The Whisper filters scare me b/c I've read about some forum members having them tear up their bettas' fins. It seems like the aquarium will end up too crowded between my decorations, filter, air tube and heater tube. So what's the best thing for my 2.5 gallon?
Thanks so much!!