One of my canister filters has "ZeoCarbon". I don't know much about this nor do I know where to buuy replacement if I need it. Do I need to replace it periodically or is it okay to leave?
As for changing it, Which canister filter do you have?
If it is a place that water flows through and you can contain the media properly, more media is always a good idea. Please note there were 2 "If" statements in that sentence. If (number 3 ) you can't meet both conditions, biomedia would not be a good idea.