Generally, swimming pool chemicals are chlorine based - bleach, essentially - but come in a bewildering variety of forms. Chlorine attacks germs and bacteria (see? It shares some properties with common household bleach), and putting the correct amount into the pool will prevent such nasties from breeding and causing illness and disease.

Chlorine has a very distinct smell, and it is likely that anyone who has ever ventured into a public pool will know this smell very well indeed.

Despite its largely beneficial properties, some people are allergic to chlorine, and this means that non-chlorine pools are becoming more and more popular. In fact concentrated chlorine can damage human cells - much like concentrated bleach can be bad if left on the skin - and is especially damaging to the eyes. If your etes have ever stung when you come out of the pool then you can appreciate where I'm coming from, here. When diluted the chlorine becomes quite harmless, and it is important therefore to make sure you put the right amount of chlorine in your pool.

There are alternatives to chlorine, but all the chemicals used will either be chlorine or bleach-based. It's a magical chemical that really does do a lot of good for you and your family.