Forum keeps knocking me off (and it won't let me edit the above post, but I can edit this one...strange), so here goes one more time....and yes I realize the original post is 8 months old. This tank is still being produced and sold, hence my reply.
Buy a Tom's in-the-tank filter. It's truly worth much more than the $15 it costs. You can clean the foam inserts and refill the carbon container yourself saving money over store bought refills.
If you want to remove the stock filter...as I'm about to do (mine totally died today)...I'm going to use an Aquaclear Mini or whatever their smallest filter is now called (it might be listed as an Aquaclear 10, I think). You'd obviously have to remove some plastic from the back of the hood, but you'd also need to remove a small bit of plastic from the built-in filter's support frame, as the Aquaclear is a tad too wide to fit in the original filter's dedicated space. A Dremel Tool would make easy work of it!!! I test fit the filter a few months back, and noticed the interference fit. Obviously, a narrower filter would make less work with the hood, but the Aquaclear allows cheaper monthly expenses (reuse your old foam, and put some fresh carbon, zeolite, or whatever, in a draw-string filter bag and you're good to go). The Aquaclear also allows adjustment of flow rate which is a plus in this small tank.
