Hello, I'm completely new to home aquariums and have never owned a fish in my life. Me and my partner have two children from her previous marriage and we are trying to introduce them to wildlife, teaching them how to tend to and care for nature. We already have guinea pigs and a hamster but now want to setup a small aquarium tank. We've found a great store that cells Coral and we already have a tank that was handed down from a friend. We haven't decided on what fish to get yes but I guess we'll want something colourful to keep the kids entertained and fish that are easy to maintain. My question was, besides the coral and tank, what other equipment do you need? I was told that a sterilization system will be required and I'd need to pick between an ozone generator or Ultraviolet system, is that true and if so, which is the cheapest, easiest to maintain and the safest for the fish? Thanks.