The one you linked to on e-bay isn't a very good type, they're tedious to keep operating well. They don't have even air distribution in the lifting pipe and won't perform as well as you'd like.
You want to look at Hydro Sponge http://www.jehmco.com/html/hydro-sponge_filters.html
The "#2" is fine for a ten gallon tank and you can take the little extender off the bottom and make it sit low like the #0. For a 20 gallon tank you can simply place two #2 towards the ends of the tank in the back and have great coverage.
I advise using Discard-a-Stone with these sponge filters since you can take the bubbly part of Discard-a-Stone and stick it directly on the lower hose nipple inside the cage (which is inside the sponge). They're cheap in bulk and I've gotten longer run time from them than from any other airstone type.
If you get your own lengths of the 1" hard clear pipe you can replace the pipes that come with the Hydro Sponge to maximize the lifting capacity for circulation and keep the blender effect of exposed bubble columns to a minimum. Figure on a half inch gap at lowest water height.