These are the tools I used


Mark area where sponge will be and drill multiple holes in the PVC pipe.


Drill hole for airline near the top of the pipe.


with a knife cut a slit in the center of the sponge going through the sponge top to bottom


slip sponge on pipe covering the holes


insert tubing in the top hole all the way to bottom of tube then pull back about 1/2", I used rubber band to attach the sponge to the slate bottom. (would usually silicon pipe to slate but being lazy and not wanting to wait for curing of silicone)


attach air line to pump and you're done.

WOW thats awesome!!! Cheap and Easy! If the pipe is attached to the slate Would you have to use the rubber bands to still hold the sponge down?

nope

That is purely awesome!

What kind of sponge do you use?

I cut up an old couch cushion. (always free on the side of the road)

Cool!
Always give stuff from the side of the road the good 'ol smell test. Smell for chemicals and urine. Both very bad things in a fish tank.

How do you clean the cushion?

cut them up about 3/4" to 1" off all side then cut into blocks, throw them in the washing machine using hot water. 1 cushion makes like 10 filters so you can be choosy on which cushions you pick up. (yes the smell test is important and run your washer a couple of time to be sure no soap in it) I've never had a problem yet with them.