Water Q&As: How does our swimming pool stay so clean?

Science Center Objects

Learn about different methods to keep swimming pool water clean and safe.

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How does our swimming pool stay so clean?

Water Questions and Answers

It is not an easy task to keep a swimming pool clear and clean. If you just set a pan of water outdoors in the middle of summer, you'll see that it will end up containing a variety of particles very quickly. People have to resort to both chemical and physical means to keep the pool water clean and safe for swimming. The water is continuously pumped through a filter to trap particles, like all those bugs that fall into the pool. To keep algae and dangerous bacteria from growing, chemicals such as chlorine are added. 

Some people have "salt-water pools," that use saline water instead of fresh water. In salt-water pools, chemical chlorine is not added to the pool water. Now, there is still chlorine in the water because the salt added to the pool water dissolves into sodium and chloride. In a salt-water pool it is not like swimming in the ocean, where the concentration of salt is about 35,000 parts per million (ppm). Salt-water pools have water at about 3,000 ppm.