The Chemistry of Swimming Pools


Swimming pools are used for many various activities from swimming laps, to learning how to swim. Swimming is a pastime that nearly everyone enjoys whether it is in the hot Summer sun or at your local indoor pool during the Winter months. A pool can be used for water aerobic classes or swim classes to teach kids or even adults how to swim. But without a pool none of that would be possible. but you can not just fill up a hole with water and call it a pool because there will be too much risk for disease, scum and pathogens. The most common chemicals used to help keep a pool clean are Bromine, Salt, and Chlorine. The pool chemistry has to be checked to make sure there is a safe amount of chemicals in a pool, a safe chlorine level ranges from 1.5 to 2.5 with a pH of 7-8.Composition of ...

      • Disinfecting agent:
        • Chlorine
        • Bromine
      • Stabilizing Agents:
        • Cyanuric Acid
      • The water
        • H2O
    • Pools have filtration system that filter out the solid pieces but they need chemicals, that are checked often to keep the sanitary of the pool up. Many pools use HClO to clean the pool because it “burns up” the interior of bacterium.
      • HClO = (H+) + ClO-
    • pH also plays a large part in keeping a pool sanitary.
      • an acceptable pH ranges from 7.2-7.8, at which HClO and ClO- are present in approximately equal concentrations.
      • If the pH drops to low the concentration of HClO rises and high concentrations of HClO can lead to the formation of Chloramines.
      • To raise the pH by adding Sodium Carbonate
        • (H+) + Na2CO3 = (HCO3-) + 2Na+

Main Chemicals, Compounds, Components

    • All chemicals need a combination of filtration and chemical treatment.
      • Pump
      • Filter
      • Heater
      • Chlorinator
      • Basin
      • Water Filter
      • Drains
      • Returns
      • PVC - Plastic plumbing connecting all of the components.

The Chemistry of Swimming Pools: Chemical composition of the components

    • Pump
    • Filter
      • Fiberglass
      • Polyester or polythene (CH2-CH2)
      • Bronze (CuSn)
    • Heater
    • Water Filter
      • Kills pollutants, microorganisms, and protects hygiene using Hypochlorous acid (HClO) and Hypochlorite Ion (OCl-)
      • Made with Fiberglass, concrete, or metal, containing a thick blend of special grade sand
    • Chlorinator
      • Uses salt (NaCl) to produce hypochlorous acid (HClO) and sodium hypochlorite (NaClO)
    • Chlorinator
      • How
        • Used mostly for salt water pools which takes salt (NaCl) to make chlorine, before a salt water chlorinator can work, the pool must already have a salt concentration of 3,000 ppm (Parts for million)
      • What
        • Through electrolytes, the salt and water break into hydrogen gas and hypochlorous acid. The gas leaves the swimming pool. The hypochlorous acid sanitizes the pool and ultimately reverts back into salt to repeat the process.
      • When
        • The chlorinator works all the time making sure all possible pathogens are not an issue and keeping the sanity of the pool up to par at all times
      • Why
        • If a pool does not have any cleaning agent (Chlorine, Bromine, or Salt) the pool will become muggy and the water sanity and clarity will be unfit for people to be in, that’s why pools are tested so often and are shut down if they are not up to the standards.
      • Where
        • The Chlorinator is used near the pump to regulate the amount of chemicals the pool has in it and make sure it is safe.
    • Water Filter
      • How
        • The water filter is used to rid the pool of dirty water by going through the filter inlet pipe, which leads to the water distribution head inside the tank. The water is pulled down through the sand which is used to catch any dirt or debris.
      • What
        • As the water is moved through the system, all the excess material caught inside, then the water flows through the pick up unit and out the outlet pipe.
      • When
        • Since a pool needs to stay clean, the unit works full time to keep all debris out of the pool.
      • Why
        • The quality of cleanliness is a big deal when it comes to pools because there is so much possibility of contracting a disease from dirty water.
      • Where
      • All pool functions are located around the pump so the main filtration unit is away from the pool to keep the electrical system dry but there are pool skimmers placed around pools to keep the filtering of water consistent throughout the entire pool and not just one area.

Chemistry's Role

    • The Chlorinator and the Filter are man made materials essential to have a pool capable of swimming in. They have to made in specific ways to be efficient and working.
    • The Final product is man made product, you can not go out and find just any hole and fill it with water and call it a pool. There are too many bits and pieces to making and maintaining a pool.
      • Chemistry in a pool involves a lot of precise measurements of water to chlorine or whatever chemical is used for the cleaning of a pool. The better that is maintained, the more pleasurable and clean a pool will be.


Information on chlorine and how it works in the water to disinfect.

Information on chemicals and their reactions.

Chemical reactions in a swimming pool.

Components of swimming pools.

parts/composition of Components (Bronze) (Fiberglass) (Chlorinator) (Filter)


Water Filter

About the Author

Sam has been involved in swimming throughout high school and has been a part of the state team since freshman year. He took interest in the sport of swimming after having two shoulder injuries that made him lose interest in contact sports. He has always been involved in out of school activities as well including participating in YSA soccer in the spring for a little fun and has been working since he was fourteen. He currently works at Great Harvest bakery. Working has taught him a lot about earning and saving money. He is not quite sure what he wants to do in life but plans on going to college after high school.