Personally, I haven't run true filter material in any of my filters for over a decade. I keep lava rock in my filters. Canister, hang on back, what have you. It serves as an excellent bio filter and I have never had to clean out a filter because of clogging, only because I was bored and wanted something to do. I ran an fx5 filter filled to the brim on a 75 gallon heavily planted tank with fish and shrimp for 2 years before I even considered opening that sucker up.
Not that the folks here aren't knowledgable (Carlos is a wealth of knowledge), check out hydraforum.com and ask some folks over there. There is some true brilliance when it comes to aquariums/planted tanks/ect there.