Unwanted bubbles

[Tempestuousfury]

I have a five and ten galon tanks with the same type of filter and bubble bars. The bars are underneath the intake tube , so I think this is part of the problem.

Anyways, very small bubbles come out of the froth that results from the filtered water. The bubles rise and pop and aren't harmful, but it's not aesthetically pleasing.

Any tips?