Hi, first time fish tank owner so I have no idea what I'm doing, but have read loads on here so I am learning. I am struggling to know where to place the filter in the tank. It's an Aqua One with a ready built filter that sticks to the side of the tank and the instructions, such as they are, seem to indicate that it should sit near the top of the water, but fully submerged. My problem is that there seems to be a number of options for the add-on bits and I'm not sure if I even need any of them, or what they're even for. Also will the filter move the water enough to oxygenate it? I'm looking at 2-3 fancy Goldfish with a view to moving to a bigger tank once I've got my head round everything. It seems a lot more 'hands on' than I imagined it would be- my Border Collie is easier to look after!