If you're looking for a new filter I would highly suggest the AZOO Mignon Filters. They don't deal with annoying cartridges and you only really need to use ceramic rings and a sponge with the setup. Cycled and cleans my tanks with ease along with it being quite cheap on amazon (about $20). I believe there is a version for smaller tanks such as 10-20gallons along with the option for larger tanks. I currently have the 150 version (I use for my 10 gal) but they also have the 60 version. I would suggest checking those out. They don't take up much room on the tank as they hang off onto the back.