Hi all,
I usually use a Maxi-jet, this is because they are relatively cheap and reliable. I've used their pumps for hydroponics, so they were my first choice, but any powerhead will do. If you think about any filter (sponge, internal, external) they are all doing the same job - a pump (in this case a spinning impeller) pulls water through a media matrix where the biological filtration occurs. The balance is between the oxygen demand of the bacteria and the amount of substrate (nitrogen, carbon etc) they consume. In our cases we can pretty well ignore the oxygen demand, we have lightly stocked tanks, plants and we massively over-filter.
Even If you look at a "good" internal filter (Eheim or Rena) the amount if biological media in the filter is fairly pathetic, you can add 10x as many filtration sites with a relatively small sponge. The other advantage is the sponge has a large surface area exposed to the highly oxygenated tank water. This "big" sponge could potentially treat a large fish load, but if you only have a light fish load it will produce high quality water even if it is only cleaned occasionally. One perceived disadvantage is that in a properly designed internal you can remove it from the tank without spilling mulm and debris in the tank, whilst with a sponge you can't. I don't see this as a problem, I put a 1000ml beaker over the sponge while it is still in the tank and the lift the the beaker out, problem solved. (a clean plastic jug would be just as good).
If you want a lot of flow you could use a higher rated pump, Maxijets come in 400 - 1200l lph, a big powerhead will need a bigger sponge, or the water will be pulled through the sponge so rapidly that the bacteria will be continually flushed out, or even if still in situ there won't be enough time for the chemical reactions of biological filtration to occur.
A coarse black ppi10 6" x 4" x 4" sponge (this is the size of sponge in the picture, with a drilled pipe like the one in the link) could go on a Maxijet 600, and would offer both excellent water movement and biological filtration for about £20. This is the exact set up I have in my shrimp tank. I screened the filter with a piece of planted bog-wood, it doesn't need to cover the whole sponge, just break up the out-line. You can even tie some java fern/moss onto the sponge if you wish. I clean the sponge about once a month (left for 2 or 3 months) sometimes if the flow stays high.
To clean I wash it under the cold tap, and just give it a light squeeze to get some of the mulm out (but not all of it).
cheers Darrel