If you purchased a new aquarium, simply rinsing it out with plain water will be enough. When you get a "new" used aquarium, the most important thing to remember is what not to do. Do not clean the aquarium with soapy water or with cleaning products. You should simply clean the aquarium with hot water. If you wish, you can mix some non-iodized salt in the water you are using to clean the tank. You may want to use a clean razor blade to scrape off any algae or calcium clusters which you can't remove from the glass with water alone.