Hi ive had a top fin power filter running on my 29g fw for almost a month now. Being a noob i added abunch of fish in probably way to early. Anyway, ive had about 9 fish for 3 weeks now, none have died and im crossing my fingers, hoping to make it through the cycling process. IN regards to changing out my carbon media that came with my power filter (HOB), is four weeks a good time to do that. Ive heard that in doin so I will be getting rid of helpful bacteria, assuming i have some. Any help would be greatly appreciated.