Maybe the pump motor is too small?
I have a few different sizes and spent some time this weekend rearranging my pumps throughout the different tanks, depending on tank size and decoration. I was amazed at how much of a difference it made.
I had this one octopus bubbler thing that my sister gave me, and I wasn't able to use it because the force of the air was shoving my angel around. Put on a smaller pump, and it works great. Moved the bigger pump to my air stone that was only working at about half capacity, and the bubbles coming out have doubled. I think they're also rated by water depth.
Something to look into.