http://www.thatpetplace.com/pet/cat/...5/category.web
The filter max 3 is the one I'm most familiar with. It comes in a box with assorted fittings so it can be attached to various size tubes in place of the strainer that comes on a filter. There are other brands and sources of purchase as well. That's just the first google hit to come up.
After looking at your signiture, there's a Filter Max 1 offered at some retailers that's a smaller version of the Filter Max 3 that I used to use on my Penguin Mini's which are the exact same filter sold as the Aqua-Tech line. Since then the Penguins have changed a little including going to a rectangular intake tube but you shouldn't have any trouble getting any of the Filter Max sponges onto the aqua-Techs with the original round intake tubes. Also the aqua-Techs come with a bio grid type material inside now like in the Whispers to serve as permanent bio-filtration. Those don't get replaced. I actually used to use the next size up in that line as my standard filter for 10 gallon tanks. I wouldn't worry about upgrading now though since as I suspected, you're carrying a large load for a 10 gallon that's going to require a larger tank to accomodate quickly. You might as well put the funding towards that project. You could add the Filter Max 3 prefilter sponge to a larger filter for a larger tank. You also have the option of adding the bio-wheels to the Aquatechs if you pick up the retrofit kits that have the new lid, the wheel, frame and bearings all in one box intended to upgrade the original Penguins to bio-wheel filters which the Aquatechs actually are even though they're marketted under a different name. If you prefilter the intake you could also skip the cartridge entirely, leave the grid in and fill the area behind the grid with additional permanent media. A cheap way to that goal is simple hair curlers. I've even gotten as fancy as getting two or three sizes so I a can pack the smaller ones inside the large getting as many as three into the space of one large one. In addition, don't fear using a light pressure rinse on the cartridge regularly for cleaning. The mini size holds together the best out of all the Penguin/Emporer/Aquatech cartridges. I just put four of the Aqua-Tech 5-15's/original Penguin Minis on my 40 gallon. I may add two more as my test tanks finish up freeing up a couple more.
You have lots of options but I think I'd make a larger tank the first goal.