i tend to overkill fltration... I couldn't stand my penguin on my 20g. the inserts are worthless and there is no room for media, and the flow through any media you put in is poor(flow around the media and not thru due to the design).
My opinion: by an aquaclear, using foam and biomedia of some kind. Buy Bio-Spira or other live bacteria. Stay away from the bottled junk on the shelf that is supposed to kick-start your bio (it's all garbage). I waited 12 weeks (using every bottle of bacteria junk) for my bio to establish, I never got a bio established, then put in BioSpira and had bio in 48hrs !! I lost 12 weeks establishing a tank.
My opinion, if you will have fish, you need aquaclear sponges or ehfisubstrat or soemthing to hold a bio filter, and that penguin is not the vehicle to do it... I have several of both.