I bought a new aquarium and filter recently and am getting ready to get it all set up today (hopefully). I already have a cycled 10 gallon tank that I threw a large bag of bio rings and a bunch of Matrix into the tank to sit maybe 2 weeks ago. I am moving up to a 45g and will be keeping the 10 going for the 2 guppy fry that are currently in a net in that tank. (my tank is super crowded with the breeder box and 2 large bags of media in it. lol) So my question is......do I need to have flow over all this media sitting in the tank or is it growing bacteria just by sitting there in the tank? I will be taking half of the bio rings in my HOB that is on my 10g as well. All of this media will be going into a new sunsun 704b. I guess I am really just asking if I should have put an airstone or something under the media bags I put inside the tank or if the bacteria will easily colonize it by it just being there in the tank.