swimming pools,resource material for students of architecture

Swimming pool From Wikipedia, the free encyclopedia

For the 2003 film, see Swimming Pool (film).

A swimming pool, swimming bath, wading pool, or simply a pool, is an artificially enclosed body of water intended for swimming or water-based recreation. There are many standard sizes; the largest and deepest is the Olympic size. A pool can be built either above or in the ground, and from materials such as metal, plastic or concrete.

Pools that may be used by many people or by the general public are called public, while pools used exclusively by a few people or in a home are called private. Many health clubs, fitness centers and private clubs have public pools used mostly for exercise. Many hotels and massage parlors have public pools for relaxation. Hot tubs and spas are pools with hot water, used for relaxation or therapy, and are common in homes, hotels, clubs and massage parlors. Swimming pools are also used for diving, other sports, and training of lifeguards and astronauts.

Pools must be sanitized to prevent growth and spread of bacteria, viruses, algae and insect larvae that can cause disease. This is done by using filters and chemical disinfectants such as chlorine, bromine or mineral sanitizers.

History The "great bath" at the site of Mohenjo-Daro was most likely dug during the 3rd millennium BC. This pool is 12 by 7 meters, is lined with bricks and was covered with a tar-based sealant.[1]

Ancient Greeks and Romans built artificial pools for athletic training in the palaestras, for nautical games and for military exercises. Roman emperors had private swimming pools in which fish were also kept, hence one of the Latin words for a pool, piscina. The first heated swimming pool was built by Gaius Maecenas of Rome in the first century BC. Gaius Maecenas was a rich Roman lord and considered one of the first patrons of arts.[2]

Ancient Sinhalese built pairs of pools called "Kuttam Pokuna" in the kingdom of Anuradhapura, Sri Lanka in 4th century BC. Those were decorated with flights of steps,

Backyard swimming pool

Contents 1 History

1.1 Swimming pool records 2 Dimensions 3 Types

3.1 Private pools 3.2 Public pools 3.3 Competition pools 3.4 Exercise pools 3.5 Hot tubs and spa pools 3.6 Ocean pools 3.7 Infinity pools

4 Other uses 5 Sanitation 6 Winterization

6.1 Closing vinyl and fibreglass pools 6.2 Covers

6.2.1 Pool cover automation 6.2.2 Pool cover materials

7 Safety 8 Dress code 9 See also

punkalas or pots of abundance and scroll design.[3]

Swimming pools became popular in Britain in the mid 19th century. By 1837, six indoor pools with diving boards were built in London, England.[4] After the modern Olympic Games began in 1896 and included swimming races, the popularity of swimming pools began to spread (reference: Encyclopedia Britannica). In 1839, Oxford had its first major public indoor pool at Temple Cowley, and swimming began to take off. The Amateur Swimming Association was founded in 1869 in England,[5] and the Oxford Swimming Club in 1909 with its home at Temple Cowley Pool.[6] The presence of indoor baths in the cobbled area of Merton Street, London may have persuaded the less hardy of the aquatic brigade to join. So, bathers gradually became swimmers, and bathing pools swimming pools.

In the USA, the Racquet Club of Philadelphia clubhouse (1907) boasts one of the world's first modern above-ground swimming pools. The first swimming pool to go to sea on an ocean liner was installed on the White Star Line's Adriatic in 1907.[7]

After World War I and the departure of "Long John" style swimming costumes, interest in competitive swimming grew. Standards improved and training became essential.

Home swimming pools became popular in the USA after World War II and the publicity given to swimming sports by Hollywood films like Esther Williams Million Dollar Mermaid made a home pool a desirable status symbol. More than 50 years later, the home or residential swimming pool is ubiquitous and even the smallest world nations enjoy a thriving swimming pool industry (e.g. New Zealand pop. 4,116,900 [Source NZ Census 7 March 2006] - holds the record in pools per capita with 65,000 home swimming pools and 125,000 spa pools).

Swimming pool records

One of the largest swimming pools ever built was reputedly in Moscow after the Palace of Soviets remained uncompleted. The foundations were converted into an open air swimming pool after the process of de-Stalinisation.[8] After the fall of communism, Christ the Saviour Cathedral was re-built (it had originally been on the site) between 1995 and 2000.

According to the Guinness World Records, the largest swimming pool in the world is San Alfonso del Mar Seawater pool in Algarrobo, Chile. It is 1,013 m (3,324 ft) long and has an area of 8 ha (20 acres). It was completed in December 2006.[9]

The largest indoor wave pool in North America is at the West Edmonton Mall and the largest indoor pool is at the Neutral Buoyancy Lab in the Sonny Carter Training Facility at NASA JSC in Houston.

10 References 11 External links

Deep Eddy Pool, built in 1915, is the

oldest concrete swimming pool in Texas, United States

Open air swimming pool 'Moscow' (1980)

[10][11] The recreational diving center Nemo 33 near Brussels, Belgium is home to the world's deepest swimming pool. The pool has two large flat-bottomed areas at depth levels of 5 m (16 ft) and 10 m (32 ft), and a large circular pit descending to a depth of 33 m (108 ft).[12]

The Fleishhacker Pool in San Francisco, California was the largest swimming pool in the United States. Opened on 23 April 1925, it measured 300 m by 45 m (1,000 ft by 150 ft) and was so large that the lifeguards required kayaks for patrol. It was closed in 1971 due to low patronage.[13]

Dimensions Length

Most pools in the world are measured in metres, but in the United States pools are almost always measured in feet and yards. In the United Kingdom most pools are in metres, but older pools measured in yards still exist. In the US pools tend to either be 25 yards (SCY-short course yards), 25 metres (SCM-short course metres) or 50 metres (long course). US high schools and the NCAA conduct short course (25 yards) competition. There also exist many pools 33⅓ m long, so that 3 lengths = 100 m. This is sometimes jokingly referred to as "inter-course". This pool dimension is commonly used to accommodate water polo.

USA Swimming (USA-S) swims in both metric and non-metric pools. However, the international standard is metres, and world records are only recognized when swum in 50 m pools (or 25 m for short course). In general, the shorter the pool, the faster the time for the same distance, since the swimmer gains speed from pushing off the wall after each turn at the end of the pool.

Width

Most European pools are between 10 m and 50 m wide.

Depth

The depth of a swimming pool depends on the purpose of the pool, and whether it is open to the public or strictly for private use. If it is a private casual, relaxing pool, it may go from 1.0 m to 2.0 m (3 to 7 feet) deep. If it is a public pool designed for diving, it may slope from 3.0 to 5.0 m (10 to 16 feet) in the deep end. A children's play pool may be from 30 cm to 1.2 m (1 to 4 feet) deep. Most public pools have differing depths to accommodate different swimmer requirements. In many jurisdictions, it is a requirement to show the water depth with clearly marked depths affixed to the pool walls.

Types

Private pools

Private pools are usually smaller than public pools, on average 16' x 32' (4.8m x 9.6 m) to 20' x 40' (6m x 12 m) whereas public pools usually start at 80 0" (25.0m). Home pools can be permanently built-in, or be assembled above ground and disassembled after summer. Privately owned outdoor pools in backyards or gardens

A boy in a shallow children's pool.

started to proliferate in the 1950s in regions with warm summer climates, particularly in the United States. In some warm-weather US locations, such as Florida and Arizona, home pools are so common that it is rare to find a new house being built without a pool being considered in the design.

Private pools are increasingly a feature of homes in greater latitudes. For example, in London many larger homes are now refurbished with indoor pools, usually in the basement or in a conservatory. In some European cities, including Munich, it is relatively common for people living in older properties to convert existing internal motorcar garages into indoor pool areas.

Construction methods for private pools vary greatly. The main types of in-ground pools are concrete, vinyl liner, and fiberglass. Above-ground pools (also called "on-ground pools") are usually cheaper to build. They are especially popular in places where ground freezing makes excavation difficult and threatens damage to the pool structure.

Inexpensive temporary PVC pools can be bought in supermarkets and taken down after summer. They are used mostly outdoors in yards, are typically shallow, and often their sides are inflated with air to stay rigid. When finished, the water and air can be let out and this type of pool can be folded up for convenient storage. They are regarded in the swimming pool industry as "splasher" pools intended for cooling off and amusing toddlers and children, not for swimming.

Some people use hot tubs and spas at home to soak their bodies in water for recreation and therapeutic reasons.

Many toys are available for children and other people to play with in pool water. They are often blown up with air so they are soft but still reasonably rugged, and can float in water.

Many countries now have strict pool fencing laws for private swimming pools, which require pool areas to be isolated so that unauthorized children younger than six years cannot enter. Many countries require a similar level of protection for the children residing in or visiting the house, although many pool owners prefer the visual aspect of the pool in close proximity to their living areas, and will not provide this level of protection. There is no general consensus between states or countries on the requirements to fence private swimming pools, and in many places they are not required at all, particularly in rural settings.

Public pools

Public pools are often found as part of a larger leisure centre or recreational complex. These centres often have

A Private Swimming pool

Rooftop pool in Manhattan.

A small inflatable "splasher" pool

more than one pool, such as an indoor heated pool, an outdoor saltwater or unheated chlorinated pool, a shallower children's pool, and a paddling pool for toddlers and infants. There may also be a sauna and one or more hot tubs or spa pools ("jacuzzis").

Public pools may belong to a hotel or holiday resort, as an amenity for the recreation of their guests. If a pool is in a separate building, the building is called a "natatorium". The building sometimes also has facilities for related activities, such as a diving tank. Outdoor pools are common in warmer climates. Larger pools sometimes have a diving board affixed at one edge above the water. Diving pools should be deep enough that divers are not injured.

Many public swimming pools are rectangles 25 m or 50 m long, but may be any size and shape desired. There are also elaborate pools with artificial waterfalls, fountains, splash pads, wave machines, varying depths of water, bridges, and island bars.

There are often lockers for clothing and other belongings. The lockers often require a coin to be inserted as deposit or payment. There are often showers ready for use - sometimes mandatory - before and/or after swimming.

Wading pools are shallow bodies of water intended for use by small children, usually in parks. Concrete wading pools come in many shapes, traditionally rectangle, square or circle. They are filled and drained daily due to lack of a filter system. Staff chlorinate the water to ensure health and safety standards.

Competition pools

Federation Internationale de la Natation (FINA, International Swimming Federation) sets widely recognized standards for competition pools: 25 m (~82 feet) or 50 m (~164 feet) long and at least 1.35 m (~4.4 feet) deep. Competition pools are generally indoors and heated to enable their use all year round, and to more easily comply with the regulations regarding temperature, lighting, and Automatic Officiating Equipment and equipment.

An Olympic sized swimming pool (first used at the 1924 Olympics) is a pool that meets FINA's additional standards for the Olympic Games and for world championship events. It must be 50 m (~164 feet) in length by 25 m (~82 feet) wide, divided into eight lanes of 2.5 m (~8.2 feet) each plus two areas of 2.5 m (~8.2 feet) at each side of the pool. The water must be kept at 25–28°C (77-82.4°F) and the lighting level at greater than 1500 lux. Depth must be at least 2 m (~6.5 feet), and there are also regulations for color of lane rope, positioning of backstroke flags (5 meters from each wall), and so on. Pools claimed to be "Olympic pools" do not always meet these regulations, as FINA cannot police use of the term. Touchpads are mounted on both walls for long course meets and each end for short course.

Inner tubes in a swimming pool.

A simplified diagram of the FINA long course swimming pool standard, used

at the World Championships and Summer Olympics.

A pool may be referred to as fast or slow, depending on its physical layout.[14] Some design considerations allow the reduction of swimming resistance making the pool faster. Namely, proper pool depth, elimination of currents, increased lane width, energy absorbing racing lane lines and gutters, and the use of other innovative hydraulic, acoustic and illumination designs.

Exercise pools

In the last two decades, a new style of pool has gained popularity. These consist of a small vessel (usually about 2.5 m x 5 m) in which the swimmer swims in place, either against the push of an artificially generated water current or against the pull of restraining devices. These pools have several names, such as swim spas, swimming machines, or swim systems. They are all examples of different modes of resistance swimming.

Hot tubs and spa pools

Hot tubs and spa pools are common heated pools used for relaxation and sometimes for therapy. Commercial spas are common in the swimming pool area or sauna area of a health club or fitness centre, in men's clubs, women's clubs, motels and exclusive five star hotel suites. Spa clubs may have very large pools, some segmented into increasing temperatures. In Japan, men's clubs with many spas of different size and temperature are common. Commercial spas are generally made of concrete, with a mosaic tiled interior. Hot tubs are typically made somewhat like a wine barrel with straight sides, from wood such as Californian redwood held in place by metal hoops. Immersion of the head is not recommended in spas or hot tubs due to a potential risk of underwater entrapment from the pump suction forces. However commercial installations in many countries must comply with various safety standards which reduce this risk considerably.

Home spas are a worldwide retail item in western countries since the 1980s, and are sold in dedicated spa stores, pool shops, department stores, the Internet, and catalog sales books. They are almost always made from heat-extruded acrylic sheet Perspex, often colored in marble look-alike patterns. They rarely exceed 8 ft² (2,400mm²) and are typically 3 ft 6 in (1 m) deep, restricted by the availability of the raw sheet sizes (typically manufactured in Japan). There is often a mid-depth seating or lounging system, and contoured lounger style reclining seats are common. Upmarket spas include various jet nozzles (massage, pulsating etc.), a drinks tray, lights, LCD flat-screen TV sets and other features that make the pool a recreation center. Due to their family-oriented nature, home spas are normally operated from 36°C to 39°C (97-102°F). Many pools are incorporated in a redwood or simulated wood surround, and are termed "portable" as they may be placed on a patio rather than sunken into a permanent location. Some portable spas are shallow and narrow enough to fit sideways through a standard door and be used inside a room. Low power electric immersion heaters are common with home spas.

The starting block of a competition

swimming pool; they were first used at the 1936 Summer Olympics.

Indoor swimming pool with mineral

water, Carolus Thermen, Aachen, Germany

Whirlpool tubs first became popular in America during the 1960s and 70's. A spa is also called a "jacuzzi" in USA since the word became a generic after plumbing component manufacturer Jacuzzi introduced the "Spa Whirlpool" in 1968. Air bubbles may be introduced into the nozzles via an air-bleed venturi pump that combines cooler air with the incoming heated water to cool the pool if the temperature rises uncomfortably high. Some spas have a constant stream of bubbles fed via the seating area of the pool, or a footwell area. This is more common as a temperature control device where the heated water comes from a natural (uncontrolled heat) geothermal source, rather than artificially heated. Water temperature is usually very warm to hot — 38°C to 42°C (100 to 108 °F), so bathers usually stay in for only 20 to 30 minutes. Bromine or mineral sanitizers are often recommended as sanitizers for spas because chlorine dissipates at a high temperature thereby heightening its strong chemical smell. Ozone is an effective bactericide and is commonly included in the circulation system with cartridge filtration, but not with sand media filtration due to clogging problems with turbid body fats.

Ocean pools

In the early 20th century, especially in Australia, ocean pools, called lidos, were built typically on headlands by enclosing part of the rock shelf, with water circulated through the pools by flooding from tidal tanks or by regular flooding over the side of the pools at high tide. There were often separate pools for women and men, or the pool was open to the sexes at different times with a break for bathers to come without fear of observation by the other sex. Segregated changing sheds and showers were provided.[15] These were the fore-runners of modern 'Olympic' pools. A variation was the later development of sea- or harbour-side pools that circulated sea water using pumps. A pool of this type was the training ground for Australian Olympian Dawn Fraser.

Infinity pools

An infinity pool (also named negative edge or vanishing edge pool) is a swimming pool which produces a visual effect of water extending to the horizon, vanishing, or extending to "infinity". Often, the water appears to fall into an ocean, lake, bay, or other similar body of water. The effect is best captured in a pool where the liner color matches the body of water it is "falling" into.

Other uses Swimming pools are also used for events such as synchronized swimming, water polo and canoe polo as well as for teaching diving and lifesaving techniques. They have also been used for specialist tasks such as teaching water-ditching survival techniques for helicopter and submarine crews and astronaut training. Round-cornered, irregular swimming pools, drained of water, were the first surfaces used for vertical skateboarding.

Sanitation Swimming pool water must be maintained at low levels of bacteria and viruses to prevent the spread of diseases and pathogens between users. Bacteria, algae and insect larvae can also enter the pool

An Ocean pool at Coogee in Sydney, New South Wales,

Australia

without help from swimmers, and cause disease to swimmers and other people in the area.

Pumps and mechanical filters are often used to filter such pathogens out of the water. Chemical disinfectants, such as hypochlorous acid, sodium hypochlorite (household bleach), bromine, salt or mineral sanitizers, are used to make the water inhospitable to pathogens. These substances also turn the water into a faded blue/green color.[16]

The subprime mortgage crisis in the United States caused many people to leave their homes without emptying their swimming pools. This resulted in the pools turning green with algae and becoming mosquito breeding grounds in less than a week.[17]

Winterization In areas which reach freezing temperature, it is important to close a pool properly. This varies greatly between inground and aboveground pools. By taking steps to properly secure the pool, it lessens the likelihood that the superstructure will be damaged or compromised by freezing water.

Closing vinyl and fibreglass pools

In preparation for freezing temperatures, an in-ground swimming pool's pipes must be emptied. An above-ground pool should also be closed, so that ice does not drag down the pool wall, collapsing its structure. The plumbing is sealed with air, typically with rubber plugs, to prevent cracking from freezing water. The pool is typically covered to prevent leaves and other debris from falling in. The cover is attached to the pool typically using a stretch cord, similar to a bungee cord and hooks fitted into the pool surround. The skimmer is closed off or a floating device is placed into it to prevent it from completely freezing and cracking. Floating objects such as life rings or basketballs can be placed in the pool to avoid its freezing under the cover. Drain plugs on the pool filter are removed after the filter has been cleaned. The pool pump motor is taken under cover. Winter chemicals are added to keep the pool clean.

In climates where there is no risk of freezing, closing down the pool for winter is not so important. Typically, the thermal cover is removed and stored. Winter sunlight can create an algae mess when a cover that has been left on all winter is removed. The pool is correctly pH-balanced and super-chlorinated. One litre algaecide for every 50,000 litres of pool water should be added, and topped up each month. The pool should be filtered for one to two hours daily to keep the automated chlorination system active.

Covers

Swimming pool heating costs can be significantly reduced by using a pool cover. Use of a pool cover also can help reduce the amount of chemicals (chlorine, etc) required by the pool. Outdoor pools

An astronaut prepares to

descend into a swimming pool

A rolled up Thermal Bubble pool

cover, used to reduce water loss from evaporation and heat loss from the

pool.

gain heat from the sun, absorbing 75%–85% of the solar energy striking the pool surface. Though a cover decreases the total amount of solar heat absorbed by the pool, the cover eliminates heat loss due to evaporation and reduces heat loss at night through its insulating properties.

The heating effectiveness of a cover depends on type. A transparent bubble cover is the most effective, as it allows the largest amount of solar flux into the pool itself. A darker cover absorbs more sunlight directly, allowing temperature to rise faster, but ultimately prevents the pool from reaching as high a temperature as a clear cover.[18]

Pool cover automation

A pool cover can be either manually, semi-automatically, or automatically operated. Manual covers can be folded and stored in a convenient location. Pool cover reels can also be used to help manually roll up the pool cover. The reel, usually on wheels, can be rolled out of the way.

Semi-automatic covers use a motor-driven reel system. They use electrical power to roll and unroll the cover, but usually require someone to pull on the cover when unrolling, or guide the cover onto the reel when rolling up the cover. Semi-automatic covers can be built into the pool deck surrounding the pool, or can use reels on carts.

Automatic covers have permanently mounted reels that automatically cover and uncover the pool at the push of a button. They are the most expensive option, but are also the most convenient.

Some pool covers fit into tracks along the sides of the pool. This prevents anything or anybody from getting into the pool. They even support the weight of several people. They can be run manually, semi-automatically, or automatically. Safety covers may be required by inspectors for public pools.[18]

Pool cover materials

There are three main materials used for pool covers: Vinyl, thermal bubble and debris.

Vinyl covers

Vinyl covers consist of a heavier material and have a longer life expectancy than bubble covers. Insulated vinyl covers are also available with a thin layer of flexible insulation sandwiched between two layers of vinyl.[18]

Thermal bubble covers

Thermal bubble covers are lightweight UV stabilized floating covers designed to minimize heat loss on heated swimming pools. Typically they are only fitted in spring and fall (autumn) when the temperature difference between pool water and air temperature is greatest. They raise temperature of a pool by around 20 °Fahrenheit, or 11 °Celsius, after being on the pool for a week. Most swimming pool heat loss is through evaporation[19] .

Bubble covers are typically applied and removed by being rolled up on a device fitted to one side of the pool (see illustration). Covers fall apart after 4 or 5 years due to sun exposure, overheating in the

Automatic Pool Cover

sun while off the pool, and chlorine attacking the plastic.

Bubble covers should be removed during super chlorination.

These covers are mandatory to be fitted to all pools in areas of Australia that have experienced drought since 2006. This is an effort to conserve water, as much water evaporates and transpires.

Debris covers

These covers are typically attached all winter, by hooked bungee cords or hooked springs connected to the pool deck, and are usually made of black or green fine PVC mesh. They are designed to stop leaf debris from entering the pool. They also provide some safety for animals and small children, but should not be relied on. They are not popular in warmer climates, due to the five to ten minutes it takes to fit/remove, making them inconvenient for repeated application and removal.

Safety Pools present a significant risk of infant and toddler death due to drowning. In regions where residential pools are common, drowning is a major cause of childhood fatalities. Therefore it is advisable to closely watch small children around swimming pools, especially private pools that do not have professional lifeguards. Adults are more likely to be aware of risks, but it is still a good idea to have more than one person around when using a private pool. As a precaution, many municipalities have by-laws that require that residential pools be enclosed with fencing to restrict unauthorized access.

In public pools there is a lower risk of accident, with trained lifeguards on duty whenever the pool is open. Because of the risk of drowning and the desire for greater safety, and technological advances that make such safety possible, more and more public pools are equipped with computer-aided drowning prevention or other forms of electronic and sometimes automated safety and security systems. Among these are the Poseidon system, Swimguard, and the Drowning Early Warning System (DEWS).

The best way to ensure safety around pools is to be educated. Knowing how a swimming pool works greatly improves safety. Long haired individuals must avoid water inlets. These inlets, also known as skimmers, are rectangular holes on the wall that are sometimes partly or completely underwater. In private pools there can be one to two inlets, in public pools five to twenty. Also to be avoided are the main drains, usually identified as round mesh covered objects on the pool floor, as poor design can occasionally cause a safety problem. Building codes and product standards have eliminated these hazards for current designs, but not all pools are up to standard.

Also the bigger the body of water, the greater force it needs to have the water circulating. Stronger water pumps are used on large pools to keep them healthy, so extra care must be taken when swimming along the sides or floor of the pool.

People with recent piercings are advised to keep those from being submerged in pools, to avoid them being infected.

Suspended ceilings in indoor swimming pools are safety-relevant components. As was demonstrated

Trained Instructors teach children how

to swim in Swifts Creek, Victoria, Australia

by the collapses of the ceiling of the Uster (Switzerland) indoor swimming pool (1985) and again at Steenwijk (Netherlands, 2001), attention must be paid to selecting suitable materials and inspecting the state of such components. The reason for the failures was stress corrosion cracking of metal fastening components made of stainless steel[20].

There is also the problem with chemical exposure from chlorinated swimming pools. Numerous scientific studies have shown increased instances of Asthma of those who swim regularly or those who work in and around indoor swimming pools. Another study with children found that kids who swam in indoor swimming pools for 1.8 hours or more a week had lung conditions similar to those of a heavy smoker. Also chlorine exposure from swimming pools has been shown to increase the risk of bladder and kidney cancer by more than 56% and it was also noted in the 2000 Olympics in Sydney Australia, where 25% of the U.S Olympic swim team suffered from some level of Asthma.[21]

Dress code In public swimming pools dress code may be stricter than on public beaches, and in indoor pools stricter than outdoor pools. For example, in countries where women can be topless on the beach, this is often not allowed in a swimming pool, especially one indoors (see swimsuit).

Dress codes are also stricter in pools than on beaches: wearing shoes, and a shirt, on a beach is acceptable, but often not in a pool. Indoor pools have stricter dress codes than outdoor pools: in outdoor pools, men are often allowed to wear t-shirts for modesty or for protection from sunburn, but in indoor pools they must usually go shirtless. At beaches, many people swim with clothes on and wear beachwear, but at pools (especially indoor pools) more minimal attire is often worn, such as lycra briefs for men or lycra one-piece tanksuits for women. Swimming with clothes on (for example, as practice for the prevention of drowning, as one might fall off a boat clothed) often results in objections from lifeguards at pools, especially indoor pools. In France, board shorts are usually not allowed for hygiene reasons. In Scandinavian countries and in particular Iceland, rules about clothing and hygiene are especially strict.[22] More recently, dress codes in many pools were relaxed to allow more modesty. Many pool operators allow people to swim fully clothed in clothes they only use in the pool if they shower in these clothes before entering the pool.

For diving from towers perhaps 10 m high, sometimes bathing suits are doubled up (i.e., men will often wear one brief inside another) so that the swimsuit does not rip on impact with the water. While splashing around on beaches, especially on urban beaches, looser fitting bathing attire that is more modest is often worn.

See also Bather load Beach Lido Pool fence Wave pool Swimming pool games

Children swimming in

clothes.

Zero-entry swimming pool Automated pool cleaner

References 1. ^ Great Bath, Mohenjo-daro 2. ^ Gaius Maecenas, or Gaius Cilnius Maecenas (Roman diplomat and patron) - Britannica

Online Encyclopedia 3. ^ WWW Virtual Library: ANURADHAPURA 4. ^ Lidos: Links and References 5. ^ British Swimming & Amateur Swimming Association : History of the ASA 6. ^ History 7. ^ TGOL - Adriatic 8. ^ DESTRUCTION (1931-1990) 9. ^ "World's Largest Swimming Pool". Guinness World Records. Retrieved on 2008-01-24.

10. ^ Edmonton.com: Travel, Tourism & Leisure accessed 15 April 2007 11. ^ NASA, Behind the Scenes: Training, accessed 7 May 2007 12. ^ BBC, World's deepest pool set to open accessed 15 April 2007 13. ^ "San Francisco Zoological Society - About the Zoo - Historic Sites". The San Francisco

Zoo. Retrieved on 2008-03-10. 14. ^ "Zesiger pool design", Zesiger sports and fitness center, MIT, accessed 2007-02-04 15. ^ "Stories from the Yamba ocean pool", Australian Broadcasting Corporation, [] accessed

2006-12-28 16. ^ The theory of colors of water in the swimming pool by Sahatchai Wanawongsawad 17. ^ West Nile quiet so far this year - The Californian / North County Times 18. ^ a b c "EERE Consumer's Guide: Swimming Pool Covers". Office of Energy Efficiency and

Renewable Energy. Retrieved on 2007-10-20. 19. ^ Department of Energy: Conserving Energy and Heating your Swimming Pool with Solar

Energy (PDF) 20. ^ M. Faller and P. Richner: Material selection of safety-relevant components in indoor

swimming pools, Materials and Corrosion 54 (2003) S. 331 - 338.(only online in German (3.6 MB))

21. ^ Chlorinated Swimming Pools Can Cause Asthma in Swimmers 22. ^ Visit Reykjavík - The official tourist website of Reykjavik, accessed 14 March 2007.

External links

How Stuff Works: Swimming pools - Explains how pools work Swimmer's Guide - Comprehensive International directory of swimming pools Pool and Spa Safety Publications from the U.S. Consumer Product Safety Commission The Association of Pool & Spa Professionals (APSP) - leading trade association of the U.S. pool/spa and hot tub industry Swimming Pool and Trade Association - UK Swimming Pool Governing Body

Retrieved from "http://en.wikipedia.org/wiki/Swimming_pool" Category: Swimming pools Hidden categories: All articles with unsourced statements | Articles with unsourced statements since April 2007

Wikimedia Commons has media related to: Swimming pools

Conceptually, swimming pools are pretty simple -- they're just big basins of water. But on a hot summer day, a swimming pool can seem like the greatest invention known to man. And as it turns out, there really is a lot of cool technology at work in your average pool -- much more than you might expect.

In this article, we'll find out how pools are built, and we'll take a look at the plumbing system that keeps the water clean and chemically balanced.

Pool BasicsSwimming pools come in all shapes and sizes, but nearly all of them, from the backyard personal pool to the water park wave pool, work in the same basic way. They use a combination of filtration and chemical treatment to continually clean a large volume of water.

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How Swimming Pools Workby Tom Harris

Inside this Article 1. Introduction to How

Swimming Pools Work2. Types of Pools3. Pool Drain Systems

4. Pool Pump Systems5. Pool Filters6. Pool Chemicals

How Pools Work

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Special thanks to Drew Waskey and Triangle Pool Management for their assistance with this article.

An apartment complex pool, mid-construction: It looks like a big hole in the ground, but it's really much more.

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A typical swimming pool needs seven major components:

� A basin� A motorized pump� A water filter� A chemical feeder� Drains� Returns� PVC plastic plumbing connecting all of these elements

The basic idea is to pump water in a continual cycle, from the pool through the filtering and chemical treatment systems and back to the pool again. In this way, the pumping system keeps the water in the pool relatively free of dirt, debris and bacteria. Some pools also include heaters in the mix, in order to keep the water at a certain temperature.

In the next section, we'll look at the different types of pools.

A typical pool system

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1. Introduction to How Swimming Pools Work2. Types of Pools3. Pool Drain Systems4. Pool Pump Systems

5. Pool Filters6. Pool Chemicals7. Lots More Information8. See all Lawn Care articles

Inside this Article

Types of Pools The main difference between different types of pools is how the basin is constructed. There are several different pool styles, each with its own advantages and disadvantages.

� Above-ground pools are the cheapest construction option, as well as the easiest to build. Most above-ground pools are made from prefabricated kits, which even an amateur can put together (though most people go with professional installers). First, the installers level off the ground to form a flat building surface. Then they assemble a perimeter track, which supports the outer wall (made of metal, plastic or wood). Next, they spread sand in the pool area and lay the plumbing. Finally, they secure the vinyl liner over the pool walls, fill the pool with water, smooth the liner and fasten it into place. As soon as they hook up the pump and filtering system, the pool is ready to go. The main disadvantage of this sort of pool is that it's less durable than other designs, and generally less attractive. It's also less permanent, which can be a good thing -- it's relatively easy to disassemble the pool and move it to a new location.

� Fiberglass pools are made from fiberglass-reinforced plastic, which has been molded into a basin shape. To install the pool, a construction crew digs an appropriately sized hole, lays the necessary plumbing, adds some sand filler and lowers the preformed pool structure into the hole. Then they level the pool, hook up all the plumbing and backfill in the area around the pool. Usually, the pool is surrounded by a concrete deck structure.

� Vinyl-lined in-ground pools are a lot like above-ground pools, structurally, but they look more like conventional in-ground designs. The construction crew digs a hole and assembles a metal, plastic or wood frame wall around the hole's perimeter. As in an above-ground pool, the crew lays sand along the bottom of the hole and secures the vinyl lining to the structural wall. These pools are a lot cheaper than other in-ground designs, but not as durable. Typically, the liner needs to be replaced every 10 years or so.

� Gunite pools are the most popular design in much of the United States. To build one of these pools, the construction crew digs a hole, puts the plumbing in place and assembles a framework grid with 3/8-inch steel reinforcing rods (rebar). The rebar rods are spaced about 10 inches apart, and secured together with wire. When the grid is in place, the crew sprays a heavy coating of gunite, a mixture of cement and sand, around the rebar. The sprayer unit combines dry gunite mix with water just before spraying -- this produces the wet concrete material. The crew trowels the gunite smooth and lets it sit for a week or so before applying a smooth finish to the rough surface. The most popular finish is called plaster (actually a mixture of cement and marble sand), but a lot of people finish their pools with special concrete paint. Gunite pools can also have tile, exposed aggregate or even fiberglass finishes. Gunite pools (and their cousins, shotcrete pools) are highly durable, and they can be built in any shape or size.

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� Poured-concrete pools are similar to gunite pools, but they're a lot harder to build. Instead of spraying concrete material around a rebar framework, concrete is actually poured into conventional wooden forms. With the rise of gunite methods, poured-concrete pool construction has mostly fallen by the wayside. In masonry block pools, the walls are constructed with concrete blocks.

While these pool designs are quite different, they all rely on the same basic plumbing and filtering systems. In the next few sections, we'll see how these components actually keep the pool going.

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Floating PoolAn in-ground swimming pool may seem like a solid, unmovable structure, but it is actually sort of like a boat -- it can float in the surrounding ground water. When the pool is empty, the ground water pressure can actually push the structure up out of the ground. This is one of the reasons why pools are filled with water year-round -- there needs to be roughly equal pressure on each side of the pool. Most modern in-ground pools have a special hydrostatic valvenear the main drain to guard against damage from ground water pressure. Basically, if the ground water pressure is great enough, it will push up on a small float, which opens the valve. When the valve opens, ground water flows in and equalizes the pressure.




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Pool Drain Systems We've already seen that the water in a swimming pool needs to circulate through a filtering system, to remove dirt and debris. During normal operation, water flows to the filtering system through two or more main drains at the bottom of the pool and multiple skimmer drains around the top of the pool.

The main drains are usually located on the lowest point in the pool, so the entire pool surface slants toward them. Most of the dirt and debris that sinks exits the pool through these drains. To keep people from getting their hair or limbs caught in the plumbing, the drains are almost always covered with grates or antivortex covers (a cover that diverts the flow of water to prevent a dangerous vortex from forming).

The skimmers draw water the same way as the main drains, but they suck only from the very top of the pool (the top eighth of an inch, typically). Any debris that floats -- leaves, suntan oil, hair -- leaves the pool through these drains. The diagram below shows a common system.






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In the system described here, the floating weir, the door at the inlet passageway, swings in and out to let a very small volume of water in at a time. To catch debris effectively, the goal is to skim just the surface level. The water flows through the strainer basket, which catches any larger debris, such as twigs and leaves. In addition to the main inlet, the skimmer system has a secondary equalizer line leading to a drain below the surface level. This line keeps the skimmer from drawing air into the pump system if the water level drops below the level of the main inlet.

The water is pumped through the filtering system and back out to returns, inlet valves around the side of the pool. This system involves a lot of suction, but if the pool is built and operated correctly, there is virtually no risk of suction holding somebody against one of the drains. The only way the plumbingsystem could apply this sort of suction is if there were only one open drain. In a safe pool, there are always multiple main drains as well as several skimmer drains, so if somebody or something blocks one drain, the pumping system will pull water from one of the other drains. This eliminates the suction on the blocked drain.

The return port

Most swimming pools also have a couple of vacuum ports, which are only used in pool cleaning. These ports attach to pool vacuum cleaners, which work something like ordinary vacuum cleaners except that they suck water instead of air. The vacuum ports may have their own pumping system, but in most pools they are driven by the main pump.

After making its way into the various drains, the water flows on to the filtering stage. In the next section, we'll find out what the pumping and filtering systems are all about.

A typical vacuum port

A pool vacuum cleaner




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Pool Pump Systems To most of us, a pool is, more or less, a big hole in the ground. We don't see most of the expensive machinery in a pool system, because it's usually tucked away in nearby pump room. But this is the stuff that really makes the pool work. The heart of the pool system is the water pump. In a typical pump system, an electric motor spins an impeller inside the pump housing. The impeller drives the water from the various drains through the filter and back out to the water inlets.

Just before it flows into the pump, the water passes through a metal strainer basket that catches leaves and other large debris that might clog up the pump.






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Pipes from the main drain, skimmer and vacuum ports lead to the pumping system.


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Next, the water flows into the filter (or, in this setup, one of two filters). In the next section, you'll find out

The strainer basket sits right in front of the pump.

The strainer basket, removed for cleaning

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what happens at this point in the system.


Light it UpThese days, most swimming pools are built with underground lights, partially for aesthetic appeal but mainly to let night swimmers see what they're doing. In one common underwater lighting design, an incandescent light bulb is sealed in a water-tight fixture, which sits inside a niche embedded in the pool wall. The insulated electrical wire runs into the fixture through a special seal, keeping water away from the conductive elements. The wire runs back to the house (or wherever the power source is) through a long tube, which is filled with water most of the way. There is enough extra wire in the tube that you can pull the entire fixture out of the niche and up above the water level when you want to change the bulb. Some people use fiber-optics to light their pools, instead of embedded incandescent fixtures. In this system, the actual light source doesn't have to be underwater, so you can skip the whole bulb-changing, water-proof electrical-component issue entirely.




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Pool Filters The filters in this system are high-rate sand filters. Sand filters consist of a large tank, made of fiberglass, concrete or metal, containing a thick bed of special-grade sand, which has a squarish shape.






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Dual sand filters

Specially made filter sand


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During filtering operation, dirty water from the pool comes in through the filter's inlet pipe, which leads to the water distribution head inside the tank. While gravity pulls the water down through the sand, the tiny sand particles catch any dirt and debris. At the bottom of the tank, the filtered water flows through the pick-up unit and out the outlet pipe.

Over time, the collected dirt and debris in the sand slows down the water flow. Pressure gauges at the filter inlet and outlet give the pool custodian an idea of the blockage level inside. If gauges show much greater pressure on the inlet pipe than the outlet pipe, the custodian knows there's a lot of collected debris in the sand. This means it's time to backwash the filter. To backwash, the custodian adjusts a number of valves to redirect the water flow. He or she closes the return pipe leading to the pool and opens the drainage pipe, which lead to the sewer system. He or she adjusts a valve at the filter to connect the pipe from the pump to the outlet pipe and connect the drainage pipe to the inlet pipe. With this arrangement, water from the pump pushes up through the sand, dislodging the dirt and debris. At the top of the filter tank, the dirty water flows out through the inlet pipe and into the sewer.

In place of a sand filter, some pool systems use a diatomaceous earth filter or a cartridge filter. In a diatomaceous earth filter, water from the pool passes through filter grids coated with diatomaceous earth, a fine powder made from the chemically inert, fossilized remains of sea organisms called diatoms. In a cartridge filter, dirty water passes through a filter made out of polyester cloth or corrugated paper. Instead of backwashing, you simply remove the filter and hose it off. After a few years (or as many as eight years), it's time to discard the old filter and put in a new one.

To redirect the water flow for backwash, the custodian turns large handles to adjust plumbing valves.


In most regions, the law dictates that all the water in the pool (or more accurately, the equivalent volume) must pass through the filter in a certain amount of time -- typically between 30 minutes and six hours. For the apartment-complex pool pictured above, that means pumping 167,000 gallons (630,000 liters) of water through the filtering system every six hours!

The pump and filter system is also connected to a well or municipal water line so fresh water can be added to the pool. This is necessary to replace water lost to evaporation, backwashing and "splash-out" (water that splashes on the deck or is carried out on people's bodies and swim suits). When it's pretty hot out and there's heavy swimmer activity, this 167,000-gallon pool could lose 300 gallons (1,100 liters) or more in one day.

Next, we'll look at the chemicals at work in a typical swimming pool.


All the water in this large pool has to pass through the filter at least four times a day.




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Chlorine is the chemical most often used to keep swimming pools and Jacuzzis free of bacteria that can be hazardous to humans. Chlorine kills bacteria though a fairly simple chemical reaction. The chlorine solution you pour into the water breaks down into many different chemicals, including hypochlorous acid (HOCl) and hypochlorite ion (OCl-). Both kill microorganisms and bacteria by attacking the lipids in the cell walls and destroying the enzymes and structures inside the cell, rendering them oxidized and harmless. The difference between HOCl and OCl- is the speed at which they oxidize. Hypochlorous acid is able to oxidize the organisms in several seconds, while the hypochlorite ion may take up to 30 minutes.

The levels of HOCl and OCl- vary with the pool's pH level. If the pH is too high, not enough HOCl is present and pool cleaning can take much longer than normal. Ideally, the level of pH in the pool should be between 7 and 8; 7.4 is ideal -- this is the pH of human tears. Once the HOCl and OCl- are done cleaning the pool, they either combine with another chemical, such as ammonia, or are broken down into single atoms. Both of these processes render the chlorine harmless. Sunlight speeds these processes up. You have to keep adding chlorine to the pool as it breaks down.

While the bacteria-killing properties of chlorine are very useful, chlorine also has some side effects that can be annoying to humans, and possibly even hazardous. Chlorine has a very distinctive smell that most find unpleasant, and some find overwhelming. There is also the "itch factor" -- chlorine can cause certain skin types to become itchy and irritated. The hypochlorite ion causes many fabrics to fade quickly when not rinsed off immediately after exiting the pool. This is why your swimsuit looks faded and worn so early in the summer.

Extremely high amounts of chlorine gas hovering above your pool can be hazardous to your breathing. Some companies have developed alternatives to chlorine, including other chemicals and ion generators. Some of these are good alternatives, but they don't achieve the cleanliness, oxidation levels or low price that chlorine provides.

Here are some interesting links:

� Chlorine alternatives, should you use them?� The Chlorine Pool Page� How does chlorine bleach work?� Can water go bad?

How does chlorine work to clean swimming pools?

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Pool Chemicals A pool's filter system does the heavy lifting in keeping the water clean, but it takes chemistry to do the fine-tuning. It's important to carefully manipulate the chemical balance in pools for several reasons:

� Dangerous pathogens, such as bacteria, thrive in water. A pool filled with untreated water would be a perfect place for disease-carrying microorganisms to move from one person to another.

� Water with the wrong chemical balance can damage the various parts of the pool.� Improperly balanced water can irritate the skin and eyes.� Improperly balanced water can get very cloudy.

To take care of pathogens in the water, you have to introduce a disinfecting agent that will get rid of them. The most popular pool disinfectant is the element chlorine, in the form of a chemicalcompound such as calcium hypochlorite (a solid) or sodium hypochlorite (a liquid). When the compound is added to the water, the chlorine reacts with the water to form various chemicals, most notably hypochlorous acid. Hypochlorous acid kills bacteria and other pathogens by attacking the lipids in the cell walls and destroying the enzymes and structures inside the cell through an oxidation reaction. Alternative sanitizers, such as bromide, do basically the same thing with slightly different results.

Chlorine is typically prepared in liquid, powder or tablet form (though some professionals use gaseous






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chlorine), and it can be added to the water anywhere in the cycle. Pool experts generally recommend adding it just after the filtering process, using a chemical feeder. If it's added directly into the pool, using tablets in the skimmer boxes, for example, the chlorine tends to be too concentrated in those areas.

One problem with hypochlorous acid is that it's not particularly stable. It can degrade when exposed to ultraviolet light from the sun, and it may combine with other chemicals to form new compounds. Pool chlorinators often include a stabilizing agent, such as cyanuric acid, that reacts with the chlorine to form a more stable compound that does not degrade as easily when exposed to ultraviolet light.

Even with a stabilizing agent, hypochlorous acid may combine with other chemicals, forming compounds that are not very effective sanitizers. For example, hypochlorous acid may combine with ammonia, found in urine, among other things, to produce various chloramines. Not only are chloramines poor sanitizers, but they can actually irritate the skin and eyes and have an unpleasant odor. The distinctive smell and eye irritation associated with swimming pools are actually due to chloramines, not ordinary hypochlorous acid -- a strong smell usually means there is too little freechlorine (hypochlorous acid), rather than too much. To get rid of chloramines, pool custodians have to shock treat the pool -- add an unusually strong dose of chemicals to clear out organic matter and unhelpful chemical compounds.

Chloramine formation is related to the second major element in pool chemistry, maintaining the right pHin the pool.

pH LevelThe water's pH is a measure of its total acid-alkalinity balance -- the relative proportion of acids and alkalis in the water (check out Chem4Kids: Acids & Bases for a description of acids and alkalis). Simply put, water that is either too acidic or too alkaline will cause undesirable chemical reactions. If the water is too acidic, it will corrode metal equipment, cause etching on the surface materials and cause skin irritation. If the water is too alkaline, it can cause scaling on the pool surface and plumbing equipment and can cloud the water. Additionally, both high acidity and high alkalinity alters the effectiveness of the chlorine. The chlorine won't destroy pathogens as well if the water is too alkaline, and it will dissipate much more quickly if the water is too acidic.

On the pH scale, zero indicates extreme acidity, 14 indicates extreme alkalinity and 7 indicates a neutral state. Most pool experts recommend a pool pH between 7.2 and 7.8. To raise or lower pH, a pool custodian simply adds acids or alkalis into the water. For example, adding sodium carbonate(soda ash) or sodium bicarbonate (baking soda) will generally raise the pH, and adding muriatic acid or sodium bisulfate will lower the pH.

Maintaining the proper balance of chemicals in the pool is a continual process, because any new element -- oils from a swimmer's body, a shot of chlorine, stuff that falls in the water -- shifts the water's total chemical makeup. In addition to pH, pool custodians also monitor total alkalinity, calciumhardness and total dissolved solids.

When you consider all the chemistry and machinery involved in swimming pools, it's clear that they really are remarkable pieces of technology. It takes a surprising amount of work and ingenuity to build and maintain these summertime staples.

For more information on swimming pools and related topics, check out the links on the next page.


Inside this Article

Fiberglass Swimming Pools - Dynamite Material For A Pool 65By Tommy B

When considering the purchase of an in ground pool materials used needs to be thought of. One dynamite material for swimming pools is fiberglass. Fiberglassswimming pools have been known for years to be the Hercules of pools because of their durability. Due to the lack of texture on the fiberglass pools algae has a hard time clinging to it. This makes these pools much more leisurely to own due to less of a need to scrub.

The manufacturer takes the fiberglass and designs and molds the fiberglass into these pools. So the pools are sold already in these shapes. The fiberglass is so easy to clean because algae and other grime are not able to grip the surface as on the other pools. Who would not like less cleaning of anything in their lives?

Concrete will have you cracking up as far as your pool aging. Fiberglass rarely cracks and withstands the passing of time in a better way than concrete. Vinyl liners are a bit better than concrete but nothing is like fiberglass. Research is needed though into which material suits you best according to what your pool design is.

Shake, rattle, and a bit of rolling happens when an earthquake hits. Earthquakes destroy many people's property. But guess what? Fiberglass swimming pools can even come through an earthquake in tact at times. The pools will shake with the earth instead of against it and keeps them from breaking sometimes.

There is a point to where the fiberglass pools may not satisfy you they come in only a select few sizes and shapes unlike concrete that can be molded into any shape or size. But you can have a certain variety as far as colors, shapes and depths. You even have a decision you can make on where the stairs are. It may be hard but you have to select your pool's size and shape options before proceeding with the rest of the project.

One thing to definitely point is that year round fiberglass pools have to have water in them. You can take the level down a bit for winter but they

Making Waves : Background InformationStudent Pages | Materials

Fast and Slow Swimming Pools:Some swimming pools are considered 'fast' while others are 'slow'. What is a fastswimming pool? A pool's walls and other components may create and reflect wavmaking it more difficult (slower) for the athletes to swim. A fast pool minimises wainterference with the athletes making it easier (faster) for the athletes to swim.

� In this section you will learn about:� Olympic specifications, rules and regulations on the design of swimming poo� the science of water waves,� guidelines for the design of your Olympic swimming pool models,� how your model swimming pool designs will be evaluated.

Rules Governing Olympic Competition Swimming FacilitMost sports have a governing body with the authority to establish rules and regulcompetitions. In the sport of swimming this governing body is La Fédération Interde Natation (FINA) located in Lausanne, Switzerland. FINA is also the governing diving, ocean swimming, water polo and synchronised swimming. The rules and regulations for swimming pools used in world championships, the Olympics and ocompetitions are published by FINA.

The rules specify the requirements for the facilities (swimming pools and lighting)components (lanes, ropes, gutters), shape, dimensions and safety. Olympic swimpools must have:

� Depth: 2.0 metres minimum,� Width: 25.0 metres,� Length: 50.0 metres (or 25.0 metres if it is a short course),� 8 2.5 metre lanes with a 2.5 metre space outside lanes 1 and 8; each lane is

separated by a rope (lane rope).

WavesThere are various types of waves. Sound and light are two types. Different types move matter in distinct ways. To reduce the water waves in your fast swimming pdesign, it is important to understand exactly how water waves move. Knowing howaves are created and how they behave will help you reduce or stop them.

Toss a small stone into a body of water. Waves are formthe point the stone hit the water. The waves form a circupattern around this entry point and spread further and furapart. There is a single wave pattern. When you look at twaves you can see the crests (high points) and troughs (points). Only a few crests and troughs are created.

Drop two or three stones at the same time into the water. Now you have more waves and these waves interact with one another.

Imagine eight lanes of Olympic swimmers! Each swimmer's motion generates a series of waves. These waves can move across the lanes and interact with one another and against the athletes in different directions, making it more difficult to swim and slowing down the athlete's times. Have you ever had to walk into the wind? Itdifficult than on a calm day. Similarly, swimming into waves is more difficult than swimming in calm water.

Amplitude

The amplitude of a wave is the difference in height between its crest and trough. greater the amplitude (height) the stronger and more intense the wave is. An athlmore difficulty swimming through larger (higher amplitude) waves than smaller (loamplitude) waves.

Reflection

When a wave stikes a surface or moves through an area whemedium's properties change, the wave will either change direreflect back.

In a swimming pool, waves which strike the sides or bottom opool reflect back. The reflected waves and original set of wavpass through one another.

This image shows waves reaching a lake shore. Notice that talmost no reflection of the waves.

Wave reflection - notice water which strikes the stick reflects back. The reflected waves pas

the waves moving towards the shore.

Diffuse Reflection

A wave may strike a body that is very rough and irregular. As the wave strikes onof the rough, irregular object it may reflect in one direction; as it strikes another pothis surface it will be reflected in a different direction. The wave can be reflected idirections at the same time. In some instances, the reflection is so small that the 'diffused' (the effects are minimal).

The AthleteAs a designer you must understand how the athlete utilises the pool. How does thswimmer move into and through the water in a competitive event?

Typically, the athlete dives into the pool at one end (the start) and swims toward topposite (turning end) of the pool. They will turn at the far (turning) end and swimthe starting point.

As the swimmer dives into the pool circular-type waves are created at the water'sAs the swimmer moves deeper into the water and disturbs the water below the suwaves are created underneath the surface of the water.

As the swimmer comes back to the surface, and begins to swim, a series of triangwaves are formed. These waves look similar to the trail behind a motor boat or a The trailing edges (the end) of these waves can strike the lane lines.

The swimmer approaches the turning end of the pool. As they touch the wall theyand swim back to the starting point. When they turn they will create waves in the direction - headed for the starting point. These two sets of waves (the waves appthe turning end and the waves leaving the turning end) will collide and pass throuanother. The waves approaching the turning end of pool can also be reflected bathese waves strike the wall. This is a critical area in pool design. Early footage of competitive swimmers (before modern pool design innovations) show swimmers swim through choppy waves in the turn.

Have you ever watched a swimming competition whathlete is significantly ahead of the others? This athmakes the turn long before the swimmers in the othIf the lane ropes do not stop waves from crossing lawaves from other lanes can interfere with the swimmslowing them down.

Photo of the 1996 Olympics (courtesy of www.kiefer.co

The lane ropes have stopped waves from crossing lanes.

As a designer you must consider all the areas discussed, and anticipate problem

Pool Design GuidelinesYour swimming pool should be a scale model of an Olympic swimming pool. The depth to length to width are:

2 : 50 : 25

or

2 : 25 : 25

for a short course pool.

You must include lane ropes. Your pool can be deeper at one end of a lane than other. You may use any material you like for your swimming pool model.

The pool designs will be evaluated as follows: Starting from the deepest end of the pool model, an action figure will be dropped towed in both directions in each of 2 lanes. The test will be repeated twice and tharranged.

The weighting for scores is:

40% pool wall reflection:

The pool model with the smallest wall wave reflection should be given the highest score in this category.

20% lane lines (ropes):

The model with the fewest waves created by lane lines should be given the highest score in this category.

20% depth:

The pool with the lowest depth and fewest waves should be given the highescore in this category.

20% physical scale:

The model with the closest appearance and scale to an Olympic swimming pshould be given the highest score in this category.

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Energy Efficient Swimming Pools - Green Pool 72

By Maria Slaby

Make your Pool Go GREEN - In a good way!

We all are hearing more and more about living ‘Green' by developing environmentally friendly living routines. Everyday more options and alternative building methods come to the foreground. Swimming in a "Green" pool is definitely within reach. Both existing and newly built pools can be environmentally friendly with just a few tweaks.

There are also many things you can do that reduce your energy impact and also save you money. Here are the most important ones to look at.

1. Your Pump - make sure it is on a timer. Reduce your run time in the winter to save on your power bill. You might run your pump 8 hours a day if it is a gunite pool and 4 hours a day if it is a fiberglass pool.

1. Your Pump Part II - look into a variable speed pump. This pump runs at a lower speed to circulate, sanitize and filter your water. The pump can be ‘kicked up' to a higher speed to run your water features. California and many other states are mandating the use of two-speed pumps. Spend a little bit now to save for years to come. You'd be amazed at the potential savings. Check out a calculation of the savings (http://www.pentairpool.com/pool_pump_calc/index.htm)

1. Pool Heating - There are three main ways to heat your pool.

Gas can be used to heat a spa quickly but it is not recommended for a pool - it would be too expensive in many parts of the country

Electric heat pumps are very efficient for heating your pool. States now are requiring pool heat pumps have a higher C.O.P rating. A C.O.P. is the coefficient of performance which is analogous to the SEER ratings of air conditioning units. The higher the C.O.P. the better. Of course, there needs to be heat in the air for the heat pump to 'steal' to heat the pool. If you are in a cold climate, the heat pump might not make sense.

Finally, solar heating is used to heat pools. There is nothing like the virtually free cost of operation for you to really love the warmth of a solar heated pool.

Regardless of the method of heating you may use - remember that a pool cover is essential for keeping the heat in your pool during the night as temperatures dip. Also, if you are having a pool built, consider skipping the screen altogether and going with fencing. Not only do you save some money on the construction, but you have a pool that is 2-3 degrees warmer.

As an aside, we should also all be looking at solar water heaters for our in-house consumption. Saving money in the pool or at the shower is still money saved. Visit our website http://www.mymermaidpool.com/ for more ideas on pool projects.

1. Chlorine Generators (Salt Systems) - If you have a gunite pool, a chlorine generator is a must. These devices take salt and through electrolysis, make sodium and chloride which is what sanitizes the water. Because of the great demand for chlorine in a gunite pool, this investment will pay off in several years. For fiberglass pools, because they use far less chlorine, this added expense is not required (but if you don't like chlorine tablets.............)

1. Piping - If you are building a pool, make sure your builder understands hydraulics. In our studies of drain-free pools (http://www.allbusiness.com/environment-natural-resources/ecology/5471798-1.html) we have learned how to efficiently circulate water in a way that reduces the wear and tear on your pump AND the length of the runtime on your pump system too. A pool with properly sized piping is one of the many small things that show the difference between pool builders.

Finally, cleaning your skimmer and filter are also helpful so that your pool can accomplish the filtration and sanitization without straining the pump. While you are at it, go change your AC filter in your house (and your car too).

Taken together, these small steps can help you save money and reduce your energy consumption for your pool. Aside from the pool itself, what could be more fun?

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