The filter I have is the one that came with the tank, I'm not sure how else to name it.
I'm using the API test strips, so I realize my readings aren't the most accurate: Nitrite levels are 0, Nitrate levels are between 0 and 20 (they're a very pale pink), and Ammonia levels tend to be around 0.5mL when I do the tests weekly. I set up the tank on 4/21/16, so almost 4 weeks ago.
I do gravel vac'ing and partial water changes once a week. I have a marimo moss ball in the tank. I forgot to mention, the tank includes 1 betta fish.