Sorry, AC = AquaClear . Use two sponges instead of the activated carbon. Everytime you run the bottom-most sponge in old tank water to clean it, swap it with the other sponge so you don't lose all your bio-bacteria. I buy an additional blue sponge from Big Al's instead of the hagen one, so it makes it easy to differentiate between the two during filter cleanings.
2 x Goldfish - $0.09
2 x Ghost Shrimp - $0.60
Look on wife's face when she found out how much I've spent on fish related gear this month - PRICELESS
If that's your budget, definitely look at the aquaclear
I have an Aquaclear 300 ( http://www.bigalsonline.com/catalog/...d1=2885;pcid2= ) and it works great on my 29 gallon. I have a bunch of tetras (18 or so), 2 oto cats, a small angelfish (which will move to a different tank in a while) and 3 small, friendly cichlids, and the filter is probably more than enough filtration for the tank.