A simple way, to use those air pump, is to make a simple drawing filter
here are the steps, Simply said
1, find the sponge, (fishtank sponge, not biodegradable, or dishwashing sponges)
2 Freeze the sponge in a bath of water.
3 find the tubing, for the drawing shaft. you can use, PVC, or the clear tubing found in fish tank stores.
4 drill many little holes, make sure you put enough and that they aren;t crazy small, but not to many. for each inch (that will be covered later with the sponge) drill about 12 HB pencil size holes.
5. get your frozen sponge and drill a hole in it the same size, or slightly smaller then the drawing tube.
6. Plug the end of the tube and feed it into the now thaw sponge.
7. get your self an airstone and some air tubing. put them into the draw tube.
8. submerge and try to squeeze out all the air from the sponge.
9. turn on the air.
NOTE: the size has to match the air pump. its kinda trial and error with a touch of logic. don;t use a basketball size sponge with a tiny airpump.
The draw tube can be completely submerged or slightly past the surface, but it can;t be to high out of the water, so cut that tube accordingly
Hope this helps