It may not be chlorine but the chloramines emitted when the water doesn't have enough chlorine. If you can smell something, that's usually a sign that there isn't enough chlorine. Most people think they can smell chlorine, but you can't until the level gets extremely high, and then you can actually taste the chemicals it reacts with. It can also be a problem with pH, or with other chemicals added. If you smell a pool you might not want to get in it.