rreloaded

Hi all, Just about to buy a 25L Hailea tank, which comes with the RP 200 filter. Just wondering if anyone knows whether the cartridge media can be replaced with our own wool/noodles? Have looked around on the internet and can only seem to find entire replacement cartridges for sale that don't really look like they can be opened up to put our own wool/noodles in? Don't really want to have to keep buying entire cartridges! Thanks in advance!