i have two cannister filters on my 150 they came with filter media already in them....filter pads...carbon bags...porclyn or how ever you spell it tubes for bacteria to grow on ...ive had them running about a year and have a well established tank and never have any water problems....the other day when i was doing some rutine maintence on the filters i realized i could easly fit twice if not more the amount of those porclyn tubes in the canisters would that in time make the cannisters able to handle more of a bioload as far as live stock in my tank????