Any area that has flow through it is going to have bacteria grow in it,only the amount of bacteria that is needed for the system is going to grow,many people use canister filter on reef systems,or biostars or other media to grow bacteria in chambers,rock does grow bacteria on it and in it so does sustrate,The main thing is keeping the prefilter clean,and the skimmer working properly,all that junk that is captured or collected will pollute your tank no matter what you are using as a biological filter,I think it is funny,people hear the word wet/dry and they panic and scream murder,but if you said biological filter then that is ok,You say bioball,they crindge,,,If the organic junk is taken out of a system before it has a chance to crystalize and become ammonia,there will not be a problem,..If you look online I can guarentee you you can find a group of people who have modified or souped up that tank,and also on you tube.........Just my two cents......I would not use to much carbon on a fish or reef tank,overuse can have a bad effect on the organisms,some people use it every so often,some use small amounts and change it every month,others even say that carbon is the worse thing to ever put on a tank ,yet the have chemipure on their tank,and brag about how wonderful it works,not realizing that it`s main ingredent is carbon.....To each their own