I have a couple of outdoor stock tanks. I have a hole drilled in my basement wall above grade, and run a couple of air lines out from my air manifold to sponge filters in the tanks. Works well, very inexpensive and easy if you have a large central air pump running your indoor tanks.
I also have holes drilled in the floor in the corners of two upstairs rooms that contain small tanks. One airline up through each to run the sponges in those tanks. Again, works beautifully...and my wife hasn't even noticed.