OK, i've been having a clear out of all the toot that accumulates under my various fish tanks (and my goodness isn't there a lot!) and i found my spare filter, a tiny little box thing that came with the 10g tank, which i soon upgraded from, but haven't used since.
I thought i'd press it into service again. My 10g is pretty well filtered, but a little more never hurts, and it'll mean i've always got a spare filter matured and working well should i need to quickly set up a hospital tank.
My question is this: for maximum efficiency and best filtering, where should i position the two filters in the tank. My thought was that they should go at opposite ends, to promote good circulation.