Last Updated on September 13, 2022


Different chemicals are used in swimming pools to maintain the water’s chemical balance. Both pool owners and swimmers must understand what chemicals are used in swimming pools before entering because some of them can cause allergies or irritation if proper precautions are not taken.

What Chemicals Used in Swimming Pools?

  • Chlorine – Chlorine is the most used pool water chemical to destroy bacteria, viruses, and other harmful organisms contained in the water. There are many different types of these chemicals, including liquid chlorine, tablets, sticks, or powder-based chlorine. Chlorine compounds dissolve in water, producing a great smell of chlorine. Chlorine is not absorbed into your skin on contact, but it can cause some irritation if there are too many chemicals in the water. This can result in dry or irritated skin, red eyes and may be accompanied by coughing.
  • Ozone – Ozone, an unstable form of oxygen (O), is broken down by ultraviolet light in sunlight to form two molecules of molecular oxygen (O). This kills most organisms present in the pool. However, ozone will not be active if there is too much organic material present, and therefore requires relatively clear water to be effective.
  • Sodium bromide – This compound can be used to lower the calcium and magnesium hardness in pool water, helping reduce the speed at which calcium scale deposits form on surfaces. The chemical also has antimicrobial properties which help keep algae growth down and speed up the purification of organic contaminants.
  • Aluminum sulfate – This chemical is used to lower water alkalinity and can also be used as a coagulant when dealing with high concentrations of metals. If not properly disposed of, it can cause significant environmental damage due to its toxicity.
  • Sodium hexametaphosphate – This is added to pool water through tablets which slowly dissolve over time, gradually distributing the chemical throughout the entire body of water. This compound helps prevent the formation of calcium and magnesium scale deposits on pool surfaces which can often be a problem with pools that use high levels of metal salt-treated water.
  • Sodium chloride – Also known as common table salt, this chemical is typically added to pool water to help raise alkalinity and lower acidity. It also helps speed up chemical oxidation and can help provide a good source of chlorine for the water.
  • Calcium chloride dihydrate – used in pools that have lower than normal calcium hardness levels and helps to quickly dissolve and raise it. The resulting increase in alkalinity also helps to soften pool water while reducing corrosion of metal pipework.
  • Sodium carbonate decahydrate – This is added in pools that have very high alkalinity levels, as it helps to reduce them and bring the pH level down closer to neutral. In concentrations of more than 80 ppm in the pool water, it can cause skin irritation or redness if touched by human skin. Exposure to high levels can also cause a burning sensation to the eyes and a loss of appetite.
  • Sodium hydroxide – This chemical can be used to lower pH levels in pool water and helps speed up chemical oxidation. It should only be added when necessary as too much can cause significant damage to pool surfaces or plants that are near the water.
  • Trisodium phosphate – This chemical is often used in pool water to help prevent foaming. It can be mixed with chlorine or other oxidizing chemicals to make them more effective at penetrating cloudy areas of the water while also suppressing heavy metals.
  • Sodium bisulfate – Also known as sodium hydrogen sulfite, this chemical compound helps speed up chemical oxidation and can help improve water clarity. In high concentrations, it can cause severe skin irritation, and if ingested it can result in vomiting or diarrhea.


Other chemicals can be added to your pool water, depending on what you want to achieve. There are pH regulators such as sodium bisulfate or sulfuric acid that maintain the pool’s pH level. Algaecides such as orthophosphoric acid that stops algae growing; anti-foaming chemicals such as silicone oil or nonanoic acid; and clarifiers such as aluminum sulfate which cause tiny suspended particles to clump together so they can be removed with the pool’s skimmer. If you want to maintain high-quality pool water, you should regularly monitor both the pH levels and the chlorine levels. You must also know what other chemicals are used in swimming pools and ensure that these chemicals are well balanced if you want to enjoy a pleasant experience in your pool.


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