Originally Posted by Link119
You should buy a single cartridge, keep rinsing the floss off when it gets dirty until the the floss is going to fall apart, then put the floss on.
Or save $5 and buy a bag of polyfill. Buying single cartridges seems harder and harder, everywhere is bundling them into 3 and 5 packs lately. A lot of those cartridges also contain carbon, which I don't run in any of my tanks. Overall polyfill filters the water better and is way cheaper than manufactured cartridges, IME.