We all agree that bacteria do not colonize the water comlumn. But I still hear people say to take a handful of gravel from an established tank. Does the gravel hold that much bacteria without the use of a UGF? I would think if there was a part of the tank with the least amount of dissolved oxygen that the bacteria like it would be in the gravel. I've been wondering this for a while now, does the gravel really hold a lot of bacteria, or is it just a leftover myth from the time when UGF ruled the world... ?
