Why is my aquarium filter that bubbles?

I have a gallon Aquarium Whips 1.5 with one of those filters and air pump Whisper. A lot of bubbles keep coming up with the water, even when clean. Is this normal? Here's a picture: http://i74.photobucket.com/albums/i274/jasonrocker12/100_0268.jpg

I have one of the filters and the bubbles are supposed to be there. The filter is made to make bubbles and oxygenate the water. That is what the box is air pump for. The bubbles push the water through the filter and oxygenate the water, at the same time. There is nothing to worry.

How to make a aquarium filter that doesnt need a pump