Over the years, I've dabbled with freshwater aquariums, but never really went into them full throttle. I've always had 10 gallon tanks with a power filter, undergravel filter, and a power head, along with the usual cheesy decorations, gravel, and various fish. My daughter currently has 2 such tanks, and I'd like to combine them to a larger one to make life much easier. I'd like to hear from the experts on what the necessities are for a freshwater aquarium. Questions I have are: What is the best gravel to use, or maybe I should say gravel type/size? Pros and cons of gravel? Can sand be used or is there something similar? Pros and cons? Is an undergravel filter needed, or are their other options for biological filtration? Is it safe to use rocks from creeks and streams for decorations? Is it safe to use wood for tank decorations or is it best to buy from a store? What is needed to have live plants in a tank? Are the requirements for a FW aquarium the same as one that houses a turtle, crayfish, frog, and fish? My daughter currently has some carnival won goldfish, some tetras, a few feeder fish that she didn't want her turtle to eat, and my pride and joy, a Banjo Catfish. I saw one of them in a book years ago, but never saw one in a store until a few months ago. As I stated, I'd like to have them in a larger tank, and that is the reason for my questions. As for the last question, I can break that down into another topic if that would be easier. Thanks in advance.