Aqualife 35l - Filter Question

[iankent]

Bought this to use as a Q tank, and now its gonna be a frog tank, but have a question about the filter! There's a little bit sticking out the side which blows water back into the tank, with a pipe attached to it which I assume goes above the water level to bring in air. problem is, I want the water to stay reasonably still for the frogs - is there any way to stop the water coming out, other than covering the hole to redirect the flow? would blocking up the hole work?

thanks