if you bought the was it the delux? it comes with the bio wheel and such. But if you have just the filter and want bio then you gonna have to do what i did. you could use the carbon media container and fill with bio of choice( i used ceramic rings) and get the blue filter pads that wraps around the carbon container. the down side with this is it only holds so much bio. option two is i used the carbon container or micrion cartridge(fill the carbon container with any mech media, i used the blue bonded filter pads) and just fill the whole outside of the filter with the bio of choice(baged it or not). The only problem with this is the rings get dirt and clogged and you have to clean it in tank water to get the large stuff and builds up out. Which is why i use the micron cartrige, the cratridge needs cleaning fairly often like the bio so i do them at the same time. You could always use a prefiter on the intake of the mag350 but i didnt like it cuz it didnt really help much. These filters suck ass when it comes to bio but excell when it comes to mech, you might wanna pick something up just for bio like another canister or hob and use the mag350 for pure mech.
