Can I use ceramic of plastic bio-ball to my Magnum canister filter. There is a container for carbon. I want to empty the carbon and add some bio material. Is that a good idea???
Agreed...it's a great idea and ceramic is the way to go.
Anything that is porous will increase the surface area even more...and those ceramic rings soak up quite a bit. Carbon is good to run in the system, but you can never beat increasing the population of beneficial bacteria.
One of my FX5s is packed with those rings and it works wonders.
Use the center plastic piece for the pleated micron cartrage and then fill the entire chamber (outside of the center tube.) with ceramic rings. Don't even bother with the carbon container.