Giving credit to your idea, but sharing with op a specific example of what I think works well on a spong+powerhead combo,
i.e. corner sponge filters should be shaped to fit the corner for best space efficiency.
Ok, makes sense. I was amused at the thought of running sponge filters or even an AC on my aquarium.
“Science, my lad, is made up of mistakes, but they are mistakes which it is useful to make, because they lead little by little to the truth.” -Jules Verne