I clicked on this Same DYI because I was curious when I first Saw it.
But my WIFE thought I was Nuts when I started Gathering up the Parts for it, But now She knows I'm Nuts, I made my Sponge Filter out of a Plastic Flower Pot and Old UGF uplift tube, Gravel, Car Wash Sponge, and of Coarse it's Driven by an Air Stone.
But HEY it Works and I SAVED me $25.00 works Great in my 29 gallon tank.
After my Wife Saw it She asked Me Whats Next, Fish in the Bath Tub?
I said Hey I've always Wanted an Indoor Goldfish Pond.