the ultimate filter?

So I finally got around to setting up my 170g turtle tank. I originally went with a Rena XP4, which, unfortunately, pooped on me when one of my turtles kicked the intake apart while I was in Disneyland 2 weekends ago. I contacted Rena and got a fairly quick response telling me that the filter was still operable, but needed to be placed much lower than the tank (I didn't mention that the filter and tank are both at ground level)

So I decided I'd try my hand at making (or should I say ghettoing) my own filter. So far, I've got two pumps rated around 110 and 300 gph, a porous plastic sheet, a coffee strainer with a synthetic weave for activated carbon (not set up yet), and a sort of overflow box. Yeah, ghetto, and suffice to say the tank isn't doing that great yet. Water changes are doing most of the work.

The requirements?
1. Eliminate the need for sponges
2. Use materials that are easier to remove and clean
3. Use transparent materials so that it's easy to tell when maintenance is needed
4. Scalable to large and small applications
5. It has to work. No dead fishes.

More to come on this subject later.