For you, you should decide the depth at which the sponge filters will sit, then select an air pump that provides sufficient airflow for that depth. Tetra can make the cheapest air pumps, but They can be just a little noisy. Each feeder presents you a Unique amount of possibilities. https://caidentjyxk.mybjjblog.com/the-definitive-guide-to-automatic-fish-feeder-33279065