Whisper 10i Sucking up Betta! Need to get tank cycled.?

I rescued a beta from some one, went to petco and bought a 2 gallon hexagon tank. Its crud, it said it had a filter, but I set it up at home, and the only thing the "filter" does it bubble, its redic. I went to the store today and bought a Whisper In-Tank Filter by tetra, set it up, and the motor is so strong, that the crown tail betta can out swim in. Any ideas what I can do? Thank you!