How do sponge filters work?

[Vertrox]

Hello! I can't seem to find a definitive answer to my question. I don't seem to fully understand how a sponge filter could be strong enough to filter an aquarium well but everyone loves them? I bought a large and medium to stack on that I bought from aquarium Co-op for my 60g tall since I heard they were so great but im still confused on how they actually filter well? I just wanted to get rid of my canister and hang on back filters since they mess up my plants so bad haha. 

[Its Hutch]

I can give you a basic run down.

When you run an airstone or just air down into the sponge filter it causes bubbles. These bubbles travel up the intake tube and pull water thru the sponge filter. The water being pulled thru the sponge is filtered by the sponge and bacteria growing on the sponge. When you go to clean the sponge filter you want to fill a bag of some sort (zip-lock) with water and place the sponge filter gently inside the bag while it is still in the aquarium. You will then start to see all the crud fall off and how well the sponge filters actually work. 

Does this answer your question? If not I am sure someone can give a more thorough answer. 

[Vertrox]

That helped a lot thanks! I think im still just surprised at how simple they are and so cheap. I just couldn't understand why everyone recommends them really because I've always had a "more expensive is usually better" mindset for my pets haha