I am setting up a quarantine / hospital tank soon. I have no use for it right now, but want to be prepared. I also have not bought a single thing for it yet. What size is best? Can I stick with a little 5 gallon, or do I need a bit bigger? What can go in the tank as far as sand/gravel, LR. Can you keep a LR/coral tank only and use it as a quarantine tank?