Organic contaminants like ammonia or nitrogen build up in a pool over time. Massive amounts of such contaminants can interact with a pool's chlorine to form chloramines, which give off that potent chlorine smell that many people associate with pools. To get rid of this harsh odor, it's necessary to superchlorinate -- or shock -- pool water back to normal chlorine levels. While it may seem counterintuitive, adding a large amount of chlorine to a pool can make the undesired odor go away. Some pools should be shocked once a week, while others can go a significantly longer time. Follow manufacturers' instructions before superchlorinating your pool to get the best results.