i have ALWAYS used a little carbon in my fitlers. It is not made for bactiera growth as some have siad. it is almost like doing a chemical teatment on your water.
I do have a aquaclear filter on my 10 gallon goldfish tank. I run two sponges and 1 section of filter floss. I find it works GREAt, i change the filter floss once a week since the stuff is so cheap. and the sponges get a good bactiera culture going.
In my 30 gallon community tank i have a Hydro Bravo filter running. The hydor filters have a small basket on the front of them for whatever media you want to place in there as a extra bonus to what is already in the filter. Once a week i replace the carbon that i ahve put in there, it is so easy to take in and out and to change. It is great. I ahve always used carbon in my fitler and from what i see, it does not hurt.
I know some people say that activated carbon will leech stuff BACK into your tank, BUT, this would not happen over a long pieord of time. If you left your carbon back in for a month or more. I change mine after a week. AND becuase my filter is nicely designed, i can take it out easy if i need to add meds.
Anyway, those are my two cents. :coffee2: