Ok, I have been searching and asking more than I would like to ask one question. I am not a beginner, it's just been so long since I have had a tank. My first tank was a 10 gallon, with RTS, Tiger barbs, and red eye tetra's. My second tank was a 125 gallon coral tank. I'm going with a 75 gallon for my first new tank. I want to use as much living organisms as possible. I was wondering if there was any particular live rocks that can be used in freshwater aquariums that will support living bacteria life?