Personally only had good experiences with AQ filters. I only have one penguin biowheel and I got it with a used setup. It actually works fine too, although it produces a really hefty current which I can't adjust at all. One thing I would mention though is that an AQ 70 would be overkill for your 20 gal. Those are really for 30+ gallon tanks. The next size down (whose name I forget because Im used to the old #s AQ had) would be more suitable. The new AQ come with inserts in the box, carbon, ammonia and sponge. Until your sponge is established, I would reccomend leaving in the carbon. After it's a bit more mature, switch out the carbon for another piece of biofiltration media or whatever else youd like to throw in.