Pool

When talking about pools and their unique visual features, the first, most noticeable qualities are that pools are often enclosed with a smooth, well-defined borders, contain still or splashing water, and are clear from treatment. The ‘Better Health Channel’ [1] states that features of a healthy pool include water that is “clear,” with the ability to “see the bottom of the pool,” with “cloudiness meaning you should test the water and take steps to improve water quality.” Oftentimes, pool water can appear blue, which has to do with the tiles or other material that make up the structure of the pool. A truly clean pool that is easily recognizable is blue due to “large volumes of water have molecules that are slightly absorbing light from the red end of the spectrum,” meaning that the red light removal will result in “the light that gets reflected from the water being slightly blue” [2].

As it is easy for bacteria to develop in water, swimming pools filled with untreated water would be an ideal place for bacteria to grow, which would create an imbalance in the water and cause irritation to the skin or eyes. To avoid this issue with bacteria, swimming pool water is treated with a disinfecting agent, often chlorine, that reacts with the water to create other chemicals such as hypochlorous acid. This product “is a chemical that disinfects the water and helps to remove debris and is a common and effective treatment often used alongside filtration to inactivate microbes that may be present in the pool water,” killing the bacteria in the water through an oxidation reaction [1]. This gives the pool water its clear appearance, though this does not leave the pool completely safe.

Ultraviolet rays from the sun can cause the chlorine agent to degrade, which allows bacterial growth to occur. Additionally, “dirt, sweat, urine, and even skin moisturizers form disinfection by-products (DBPs)” that consume a pool’s chlorine [3]. This growth makes the water become cloudy in appearance, and to counter this, a stabilizing agent, often cyanuric acid, is added and reacts with the chlorine to protect against degradation. Oftentimes, if pools become neglected, this cloudy appearance will develop and pools that are normally blue will take on a “green pool” appearance, where these pools often “contain algae and can be breeding grounds for insects” [4].

References

[1] Better Health Channel. (2017, March 29). Swimming pools - Water Quality. Retrieved (2021, July 21), from https://www.betterhealth.vic.gov.au/health/HealthyLiving/swimming-pools-water-quality

[2] CNN. (2016, August 12). Why Are Swimming Pools Usually Blue?. Retrieved (2021, July 21), from https://www.cnn.com/2016/08/12/sport/why-are-swimming-pools-blue/index.html

[3] Chemical & Engineering News (C&EN). (2016, August 1). The Chemical Reactions Taking Place in Your Swimming Pool. Retrieved (2021, July 21), from https://cen.acs.org/articles/94/i31/chemical-reactions-taking-place-swimming.html

[4] Medium. (2018, July 18). Swimming Pool Detection and Classification Using Deep Learning. Retrieved (2021, July 21), from https://medium.com/geoai/swimming-pool-detection-and-classification-using-deep-learning-aaf4a3a5e652.