Download Pool Tip #22: Hypothermia (PDF format, 18KB)

Body heat is lost through four processes: radiation (still air surrounding the body), conduction (contact with a cold object), evaporation (sweating), and convection (air or water movement around the body). Swimming in an attempt to stay warm will actually increase the rate at which heat is lost through convection, and will speed up the onset of hypothermia. Immersion hypothermia is a lowering of the body core temperature which occurs when cold temperatures cause the body to lose heat faster than it can be produced. The onset of hypothermia is also affected by: wind velocity; air temperature as well as water temperature; length of exposure to the cold; the person’s age, body size, build, level of mental and physical fitness; and, the amount and type of protective clothing worn.

Initial symptoms of hypothermia include shivering, rapid and involuntary muscle contractions, and bluish coloring. Reduced blood flow to the extremities also occurs due to the “mammalian diving reflex”, a series of bodily functions that reduce circulation to most parts of the body except vital organs, and which is triggered by sudden face contact with cold water (less than seventy degrees F). Hypothermia will progress toward sleepiness, unconsciousness and eventual death. The proper response to unexpectedly finding oneself in cold water is to stay where you are, use clothing for flotation, and use either the heat escape lessening posture (H.E.L.P.) or huddle together if there is a group. Do not attempt to survival float or swim to safety.

To avoid the possibility of afterdrop which might trigger ventricular fibrillation, first aid for mild hypothermia involves gradual rewarming by showering, covering up, getting out of wet clothes, and drinking warm liquids. Alcohol should not be consumed because it causes blood vessels to dilate and increase heat loss. Also, hypothermic victims should not smoke since nicotine reduces circulation to the skin.

Download Pool Tip #21: Swimming Immediately After Eating (PDF format, 18KB)

Was your mother right? Is it dangerous to swim after eating? Do you really have to wait at least thirty minutes after eating to avoid stomach cramps and possibly drowning?

This “old wives” tale has been around for quite some time and has been perpetuated generation after generation by well meaning, but incorrectly informed, parents. There is not even one recorded case of anyone experiencing stomach cramps and drowning while swimming immediately after eating. As a matter of fact, long distance swimmers eat while in the water swimming their endurance events.

Consumption of low fat, high carbohydrate foods can be nutritionally beneficial to elite competitive swimmers. However, not eating at all, or eating particular foods immediately before swimming will neither harm nor enhance the swimming ability of most typical recreational swimmers.

Engaging in intense exercise immediately after eating a heavy meal is not beneficial to proper digestion. You shouldn’t try to run a marathon immediately after consuming a Thanksgiving feast, nor should you compete in a long distance competitive swimming event. However, it wouldn’t hurt to go for a short walk around the block after a moderate meal, and neither would it be dangerous to swim a few laps. Just use common sense to decide when it’s appropriate to swim after eating.

Download Pool Tip #20: Acid Washing (PDF format, 21KB)

If it’s necessary to acid wash your swimming pool, make sure you do so in a proper and safe manner. Incorrectly acid washing a pool can be extremely dangerous to individuals performing the task, can be damaging to the pool surface, and harmful to the environment.

Before you start, read the Material Safety Data Sheets (MSDS) for all the chemicals you will use during the procedure. Purchase and wear the personal protective gear recommended in the MSDS sheets. The gear will include protective clothing that covers all areas of exposed skin, a full face shield or goggles, half mask respirator with fresh acid cartridges, rubber boots and gloves.

Visually inspect the pool, looking for discoloration, mineral staining, ghosting, plaster etching or mottling, chipped tile, broken steps, cracks, scaling, and other problems which should be corrected while the pool is empty.

Drain the pool to the sanitary sewer or other approved location, then closely inspect the entire surface of the empty pool. Tap the walls and pool bottom looking for loose plaster or hollow spots. Sand off any excessive calcium build-up. Make sure the pool is dry and you have taken all appropriate safety precautions to avoid electrocution if you’re working with an electrical sander.

Rinse down the whole pool with water from a garden hose using a high pressure nozzle. Mix water and tri sodium phosphate (TSP) in a plastic sprinkling can. Add about 1/4 cup of tile soap to the mixture. Pour the TSP mixture from the deck down, a small area at a time. Scrub with an industrial pool deck brush to remove the oil residue and scum that has built up over time. After completing the pool walls, scrub the pool bottom in a similar manner. Be careful not to slip and fall. Rinse the entire pool with fresh water again.

Make sure that the area you’re working in is extremely well ventilated. Acid fumes are heavier than air and will have a tendency to collect in the bottom of the pool. Don’t work alone. Both you and your partner should be knowledgeable in first aid procedures for acid burns, and respiratory emergencies in case one of you is overcome by fumes.

Prepare a mild acid and water solution. Add acid at a ratio of no more than 1 part muriatic acid to 4 parts of water. Remember to add the acid to the water already in the bucket, not water to the acid. Using a long handled brush, scrub a small area of the pool at a time until the surface feels like fine sand paper. Rinse frequently. Keep the rinse water on at all times, and move the sump pump around to avoid leaving an impression known as a pump “foot print” on the pool bottom. Neutralize the acid, and dispose of the neutralized solution in an approved manner.

After completing the acid wash, rinse the pool several times with fresh water. Pour sodium carbonate (soda ash) down the main drains to help neutralize any acid that may have gotten into the drains and recirculation lines. Neutralize the acid on the pool shell, by again scrubbing the entire surface with a mixture of TSP and water, as previously described. Rinse the surface one final time with fresh water.

Download Pool Tip #19: Cleaning & Disinfecting Pool Decks (PDF format, 19KB)

Pool decks should be both cleaned and disinfected regularly to prevent the spread of disease as well as the slipperiness that results from biofilm growth. Depending on the type of deck surface material –– brushed concrete, textured modified cement or other cementious coatings, ceramic tile, rubber granules, stone, brick, or epoxy aggregate, cleaning procedures may vary slightly. Always follow the manufactures recommendation for properly cleaning and maintaining the surface.

When decks are large enough, the purchase of a commercial steam cleaner is probably warranted. (Note: Pressure washers and steam cleaners are not the same thing). Cleaning and disinfecting decks by hand would just be too time consuming. But in smaller facilities, the following procedures are recommended.

Dirt, grease and scum can be removed by scrubbing the decks with a stiff brush and any of a number of non abrasive commercially available cleaning solutions. Read the MSDS sheet or check with the distributor to make sure that the cleanser or detergent is compatible with pool water in case some of it gets into the pool. The decks can also be cleaned using TSP (tri sodium phosphate) which can be purchased at most hardware stores. Use one cup of TSP to one gallon of water. Use a pressure washer, or rinse with a garden hose with a high pressure nozzle.

Remember the old saying, “you can’t clean germs –– you have to kill them”. To kill bacteria and other harmful pathogens, pool decks should also be disinfected. Commercial disinfectants are available, but the least expensive method of disinfecting a pool deck is to spray a mild solution of 1 part 10% – 15% sodium hypochlorite (liquid chlorine) to 20 parts of water onto the deck. Use an air pressure sprayer and wand purchased specifically for this purpose at the local hardware or gardening store to apply the disinfectant solution to the deck. Rinse with fresh water immediately afterwards.

Download Pool Tip #18: Use of Carbon Dioxide for pH Control (PDF format, 21KB)

Gaining popularity in the past few years, carbon dioxide is rapidly replacing muriatic acid as the product of choice for lowering pH in public pools using sodium hypochlorite or calcium hypochlorite as the primary sanitizer – oxidizer.

Carbon dioxide is often delivered to swimming pools in 50 pound, high pressure tanks which require the operator to frequently move and exchange cylinders. Single and dual tank feed units and regulators are sold. Rapid need for CO₂ can cause the injector to, literally, freeze up.

Most heavily used pools opt for purchase of a permanently installed, 400 pound or greater, low pressure, bulk, stainless steel cryogenic tank. The tanks are sold with non freezing regulators and pressure gauges. The tanks are typically 20 to 24 inches in diameter and 5 to 6 feet tall. The pool owner then signs up to have the bulk tank refilled or topped off on a weekly or regular basis by a carbon dioxide supplier. The cost of purchasing the bulk tank and related equipment is in excess of $2,000.00, but the price of bulk CO₂, including delivery, is less than 35 cents per pound.

The CO₂ regulator is connected to the pH/ORP controller, and carbon dioxide is injected on demand into the pool return line. The injection point should be last in line after the pump, filter, heater, and chlorine injection port. Or more appropriately, using a booster pump and an efficient gas transfer Venturi injector, the carbon dioxide should be fed into a slip–stream of water which then joins the main return stream.

Carbon dioxide when mixed with water produces carbonic acid, a fairly mild acid which acts to reduce the pH of pool water. If a controller or feeder malfunction occurs, the water will become carbonated, or fizzy like a soft drink, but the mild acid doesn’t give off fumes, and won’t be quite as corrosive or damaging to the pool environment and bathers, as a more acidic pH adjustment product would be.

Since CO₂ gas is odorless, and heavier than air, the chemical storage room should be mechanically ventilated, with exhaust vents located near floor level. Like any pressurized gas tank, the CO₂ tank must be bolted or securely chained to the wall. For safety reasons, the chemical room door should always remain open when the pool operator is inside the room. If a leak should occur, there is a danger of carbon dioxide displacing the oxygen, causing the operator to suffocate.

Unfortunately, carbon dioxide when added to pool water also forms bicarbonates, and causes a rise in total alkalinity. The total alkalinity then needs to be lowered with sodium bisulfate or muriatic acid, the purchase and storage of which the pool operator tried to eliminate by using carbon dioxide for pH control in the first place. The sodium bisulfate or muriatic acid used to lower total alkalinity then causes a drop in pH, which the controller then interprets as being too low. The controller sends a signal to the CO₂ regulator to inject CO₂ to bring up the pH, which raises total alkalinity… For this reason, use of carbon dioxide is not recommended for all pools. Pools using calcium hypochlorite as their primary chlorine product, pools with oversaturated water problems, pools with source water high in total alkalinity and calcium hardness, might be better off remaining with muriatic acid for pH control.

Download Pool Tip #17: pH (PDF format, 37KB)

pH is the log of the reciprocal of the concentration of hydrogen ions in a volume of water, or simply a measure of the acidity or alkalinity of the pool water. As the number of hydrogen ions in the solution increases, the pH decreases and the water becomes more acidic. Conversely, as the number of hydrogen ions in the solution decreases, the pH increases and the water becomes more basic.

pH is measured on a logarithmic scale from 0 (acids) to 14 (base), with 7.0 being neutral. Since pH is the negative base 10 logarithm of the hydrogen ion concentration of water, it can be expressed, for example as 0.0000001, which can be written as 1.0 x 10 – 7 , which is the same as saying the pool water has a pH of 7.0.

Keeping pool water within ideal pH ranges increases bather comfort, and prevents damage to the pool, its components and equipment. Ideal pH levels depend on the other four components of water balance (total alkalinity, calcium hardness, water temperature and total dissolved solids), but typically range from 7.2 to 7.8.

Low pH levels cause chlorine to dissipate rapidly. Equipment corrodes, and pool surface materials etch or crack.

At high pH levels, less hypochlorous acid (HOCl) forms and chlorine becomes less effective. ORP levels plummet, algae growth may increase, the water clouds, scaling occurs and circulation pipes calcify, and filter runs (the time between backwashing filters) shorten.

As you’ve probably noticed, pH levels fluctuate constantly. This problem is magnified if total alkalinity levels are permitted to drop.

Pool chemicals, rain, air pollution, the fresh make–up water added to the pool, plaster and other pool surface materials and equipment the water comes in contact with, and waste products introduced into the pool by swimmers, all cause the pH to change. Some products like muriatic acid, cyanuric acid, sodium bisulfate, and trichlor tablets are acidic and cause the pH to drop. Others, like dichloro-s-triazinetrione or carbon dioxide are somewhat neutral. While other chemicals like sodium hypochlorite or sodium carbonate are alkaline.

To keep pH in the proper range, the pool operator must test frequently using a color comparator test kit, colorimeter, test strips or pH meter, and adjust as necessary.

Several chemicals are sold for the purpose of adjusting pH in pool water. To raise pH, sodium carbonate (soda ash), sodium hydroxide (caustic soda), and sodium sesquicarbonate are recommended. Commercial grade hydrochloric acid (muriatic acid), boric acid, sodium bisulfate (dry acid), and carbon dioxide (CO₂) are most often used to lower the pH of pool water.

Download Pool Tip #16: Effective Pool Barriers (PDF format, 37KB)

Effective barriers are needed to prevent unattended children from gaining access to a pool or pool area when the pool is temporarily closed between class sessions or for the evening, or shut down for the winter season or for lengthy repairs. A commercial pool should be surrounded by a fence, wall, building, or other barrier that completely encloses the pool area and prevents trespassing or foot traffic through the area. Other protective devices such as alarms and surveillance equipment, safety covers, posting of meaningful signage, and the institution of security patrols may also be effective in deterring trespassers. Pool owners should be reminded that barriers are not a substitute for active supervision. Unattended children should never be permitted in the pool area. Direct supervision by a responsible lifeguard, teacher, parent or other adult possessing swimming and basic rescue skills is the only sure way to prevent pediatric submersion accidents, drowning and other serious accidents around a pool.

Barriers should installed in compliance with local codes and industry recommendations in order to lessen unauthorized entry into the pool area. Because of the obvious need to restrict access to pools in order to protect the public, barrier code requirements have been adopted by most communities. State and county health and safety codes, building codes promulgated by associations such as the: Building Officials Code Administration (BOCA), the International Conference of Building Officials (ICBO), Southern Building Code Conference, Congress of Building Officials of America (CABLE); and model codes developed by agencies or organizations such as the National Spa & Pool Institute (NSPI) or the U. S. Consumer Product Safety Commission have all clearly defined what they consider to be effective barriers. However, no device or combination of barriers is fail-safe nor do they guarantee protection.

A properly installed pool barrier fence should not have any openings, external footholds or handholds, indentations or protrusions, or horizontal members which would make it easy to climb. The fence should be installed in a way that prevents other objects, building walls or permanent structures from being used to climb into the pool area. It should not be possible for a young child to slip through any holes or spaces in the fence, or between the bottom of the fence and the ground. Fences and gates should be constructed so that there is less than 2 inches of space between the bottom of the barrier and the ground or pool deck. There should be no holes or spaces in the fence where children could slip through. Vertical members in the barrier should not be more than 4 inches apart, and should not permit a block or sphere 4 inches in diameter to pass through. On ornamental iron fences, the distance between the tops of horizontal members should be greater than 45 inches apart to make them difficult to climb.

In his evaluation of data collected by the U. S. Consumer Product Safety Commission in studies of the physical measurements of over 8,000 randomly selected children living in the U. S., Elliott Stephenson reported in an article entitle “Unsafe Guardrails: The Silent & Inviting Trap” published in the July/August 1993 issue of Fabricator, that approximately one half of all 13 to 18 month old children can successfully pass through a 5 inch wide opening, but that none of the children over one year old could pass through a 4 inch wide opening. Measurement of head size and chest depth of the children in the study showed that approximately 95% of all 10 year olds have head widths of less than 6 inches. The chest depth of 95% of the 7 year olds tested was less than 6 inches. Study results indicate a need to space vertical members in barrier fences no more than 4 inches apart. Fences with openings of 5 or 6 inches or more will not prevent young children from squeezing their bodies through the openings in the fence.

Gates in a pool barrier fence should open outward away from the pool and should be at least as high as the required height of the fence. The gate should self-close and positively self-latch from any open position. Test the gates by opening them and allowing them to close and latch from several different distances with varying amounts of force. Regardless of whether the gate is let go slowly from a few inches or slammed with a great deal of force from several feet, the gate should always close completely and stay latched. Access gates should be locked when the pool is not in use or supervised and the locking mechanism should be mounted on the inside of the gate, located at least 4 feet off the ground, and more than 6 inches below the of the top of the gate. To prevent access to the latch from the exterior of the gate, the latch should be protected by a rigid webbing, shield or plate with openings no greater than 1/4 inch diameter, and installed to either side, below, and above the latch to the top of the gate.

Safety covers which meet strict performance standards (set in the U.S. by the American Society for Testing and Materials in ASTM standard F1346-91) can be installed to prevent access to pool or spa water. The covers have a continuous connection between the pool and deck and are installed in a track, rail or guides, or otherwise locked or secured into the deck. They are capable of supporting a 400 pound per square foot load. Safety covers bear an identification label indicating the name of manufacturer and installer and compliance with ASTM safety cover standards. They are provided with automatic auxiliary pumps or designed in a way which prevents the accumulation of standing water on top of the cover.

Emergency exit doors leading from the pool deck should remain unlocked at all times. Crash bars on the doors should be tested to make sure they are operational.

Invisible infrared or light beam alarms can be installed to detect unauthorized entry onto a pool deck, before an intruder has a chance to get in to the water. Sensors can be installed to transmit a radio frequency to receivers, or light to photoelectric cells. When a human body passes through the beam within the detection range, infrared energy is emitted or a break in the light beam occurs and an alarm is triggered.

Pool alarms can be installed to warn of unauthorized entry into the pool itself or to warn that children or pets have accidentally fallen into a pool. Underwater electronic sensors and medallions, pressure wave tubes, floating surface wave motion devices, or sonar devices can be purchased and easily installed. Most are self-contained and battery operated, and are either permanently mounted, float on the water surface, or are temporarily installed on the edge of the deck. The various sensors either detect an electronic signal emitted by the wearer of a special medallion, detect pressure changes which occur when an object falls into the water, react to wave motion or changes in water surface tension, or perceive a breach in a sonar beam between ultrasonic transducers installed on the walls of the pool below the water surface. To be effective, alarms should be activated as soon as the pool is closed for the day and no longer directly supervised, and continuously during seasons of the year when the pool is not in operation and open for use by swimmers.

A computerized drowning detection system, sold under the brand name Poseidon, has also recently been introduced to the U.S. market. The system utilizes a central processor, overhead and underwater digital video cameras which watch swimmer behavior constantly, a fiberoptic network, flashing lights and buzzers, touch sensitive displays which allow supervisors to zoom in on any area of the pool, and alarm pagers worn by lifeguards or supervisors. The computer, using mathematical algorithms and proprietary technologies developed by the manufacturer, can process the video in real time, record the events, identify unusual situations and can detect someone who is immobile or slowly sinking to the bottom of the pool, indicating a possible drowning, all within 10 seconds. The alarms sound, lights flash, and pagers alert supervisors to the exact coordinates in the pool where the victim is located and the elapsed time in seconds since detection.

For a deterrent to be effective, regular inspection of barriers and proper preventative maintenance is also crucial. Blocking open or forgetting to lock doors or gates, not maintaining fences according to manufacturers’ recommendations, ignoring or disabling alarms, or not installing covers, will render any barrier system useless.

Download Pool Tip #15: Swim Suit Damage from Chlorine (PDF format, 20KB)

Chlorine is a bleach commonly used to whiten and brighten clothes. After many washings, colors do begin to fade and clothing fibers do start to disintegrate. Clothing materials exposed to any amount of bleach, however small, will eventually fade. However, good quality swim suits (as compared to “lay around on the beach and get a tan” suits) are now manufactured from chlorine resistant materials which hold up better in chemically treated pools.

Most swim suits available today are made with either Lycra or Antron fibers. Lycra is Dupont’s trademark for its Spandex fiber, and Antron its trademark nylon fiber.

Lycra, a polyurethane (polyester) based elastomer, is always blended with other fibers. Lycra is what allows the bathing suit to stretch. Some Lycra blends have a higher resistance to chemicals. They have long, strong, flexible fiber strands that resist breaking when exposed to chlorine, and are resistant to body oils that break fibers. (More sweat, more body oils and fats at higher temperatures).

Some suits are made of Antron rather than Lycra. They are shiny, durable, resist fading from repeated washings and exposure to sunlight, and dry quickly.

Weights and quality of threads, elastics, and fabric weights used in swim suits also influence the life expectancy of a suit.

Additional information about swim suit fabrics and proper care of suits can be obtained from swim suit manufactures such as: Peli–Guard Lifeguard Products, 1131 Victor Street, El Cajon, CA 92021, (619) 447-7946.

Interestingly though, clothes washed in typical washing machines are exposed to much higher levels of chlorine than are bathing suits worn by bathers in swimming pools. Most commercial pools maintain free chlorine levels of between 1.0 and 10.0 parts per million (ppm). A standard capacity washing machine holds approximately 40 gallons of water. As Clorox advertises on TV, you should add a full cup (8 ounces) of 5% chlorine bleach to the wash load. This is the equivalent of adding 4 ounces of 10% sodium hypochlorite. The dosage required to introduce 1 ppm of 10% sodium hypochlorite to 10,000 gallons of pool water is 12 fluid ounces. Therefore, adding four ounces of sodium hypochlorite or the equivalent 8 ounces of Clorox to my wash water raises the chlorine level to approximately 83 ppm.

Swim suits fade and disintegrate as a result of repeated low level chlorine exposures, but more damage is actually caused by unbalanced (aggressive) water conditions, and the effects of body fats and oils on fabric. Surprisingly, suits worn by individuals working in warm water pools sanitized–oxidized with brominated compounds (non bleach halogens) actually disintegrate faster than the same suits worn in chlorinated pools –– indicating more of the suit damage is actually caused by body fats and oils released as a result of warm water exposure than from sanitizer–oxidizer exposure.

Download Pool Tip #14: Chlorine (PDF format, 34KB)

History

Chlorine was discovered in 1774 by Swedish pharmacist Carl Wilhelm Scheele. Scheele was performing an experiment which involved the mixing and heating of manganese dioxide and “marine acid” (hydrochloric acid). The yellow–green gas that resulted was chlorine. But, it wasn’t until 1810, that English chemist, Sir Humphrey David proved that chlorine was a separate element.

In 1895, Olin Corporation (then known as the Mathieson Alkali Company) opened its first chlorine plant to manufacture calcium hypochlorite. In 1909, the Niagara Alkali Company discovered a way to make chlorine into a liquid form by cooling and pressurizing gas chlorine. Then in 1927, Olin Corporation began manufacturing the HTH brand of calcium hypochlorite for swimming pool disinfection.

Chlorine Facts

Chlorine is the 17th atomic element, and a member of the halogen family of elements. Chlorine gas is about 2.5 times heavier than air, and liquid chlorine is 1.5 times heavier than water. Chlorine is slightly soluble in water, has a distinctive odor, and is greenish–yellow in color. Chlorine is neither flammable nor explosive, but it is combustible if it reacts with other materials. Because it is highly reactive, chlorine is found in nature only in combination with other products.

Chlorine is made today by passing an electrical current through a solution of salt water. As by–products of chlorine formation, sodium hydroxide (caustic soda or lye) and hydrogen gas are also produced.

Other Uses

Interestingly, although the general public primarily associates chlorine with swimming pool water disinfection, less than 1% of chlorine produced, in the form of elemental gas chlorine and chlorinated compounds, is used for pool water treatment.

In addition to pool water treatment, chlorine has thousands of other uses. Chlorine is used to treat drinking water to make is safe for human consumption. It was first used for this purpose in 1904 in Lincoln, England to stop the typhoid epidemic that had been plaguing the city. Chlorine was first used in the United States in 1908, to treat the municipal water supply in Jersey City, NJ. Today, more than 98% of the U.S. drinking water supply is treated with chlorine.

One of chlorine’s initial uses was as a bleaching agent to whiten clothes. The French were whitening and brightening their clothing with chlorine as early as 1790. Chlorine was used as a chemical weapon by the Germans in World War I. Today chlorine is used in the manufacture of explosives. Inhalation of diluted chlorine was popular as a treatment for the common cold during the 1920s.

Today, chlorine is used for cleaning and disinfecting, bleaching paper, food preparation, sewage treatment, and in the manufacture of thousands of medical, industrial and common household products including solvents, gasoline, transmission fluid, rocket fuel, pesticides and herbicides, cosmetics, perfumes, and deodorants, and pharmaceuticals. Vinyl plastics, from food wrap and home siding materials, to PVC pipe and vinyl liners all require the use of chlorine.

Environmental and Health Concerns

Chlorine is a respiratory irritant. Death can result from lengthy exposure to high concentrations of chlorine in air (greater than 50 ppm), or 300 – 400 ppm exposure for 30 minutes (IDLH 10 ppm). Health concerns over chloroform exposure, and carcinogenic by-products such as MX (a compound produced when chlorine reacts with organic material in water), continue to be studied by researchers at the National Cancer Institute and the National Institutes of Health.

Chlorine is hazardous to aquatic plants and fish, and can certainly damage vegetation, but some environmental groups’ campaigns to ban chlorine are over broad. Environmental concerns over spills, disposal of chlorinated pool water, and the release of chlorine into the environment have introduced secondary containment requirements and neutralization tank installment to the pool industry.

Without chlorine, cholera, typhoid fever, dysentery and other water borne diseases would be rampant. The lifespan of the average American would be shortened.

Over 10 million tons of chlorine are used annually in North America. A ban on the use of chlorine would have an economic impact in the trillions of dollars.

Supplemental and alternative products for pool water treatment continue to be introduced, but currently no single, stand alone product or chemical, works as well as chlorine for both sanitizing and oxidizing recreational pool water.

Download Pool Tip #13: Floating in Fresh Water vs. Salt Water (PDF format, 19KB)

Weight of water is what causes a person, or any other object to sink or float. Fresh water weighs approximately 62.4 pounds (28.3 kg) per cubic foot (0.028 cubic meters). There are 7.48 gallons (28.3 liters) per cubic foot, so one gallon (3.78 liters) of fresh water weighs approximately 8.33 pounds (3.77 kg). Weight of water varies depending on temperature and impurities such as salt and minerals dissolved in it. Therefore salt water is heavier than fresh water, so it can support more weight.

Again remembering Archimedes’ Principle –– you will sink if your weight is greater than the weight of the water you displace. You have to push away, move aside or displace water to get in it. If the weight of the water you displace is greater than or equal to your weight, you will float. For example, a 150 pound (68 kg) person who displaces three cubic feet (0.085 cubic meters) of water (or 192 pounds or 87 kg of water) will float. And, they will float better, the more dense the water.

Although as a generalization, women do float better than men, other categorizations such as age, height, and race have nothing to do with swimming ability. Anyone, regardless of physical abilities or limitations, can learn to swim. The main factor influencing buoyancy is body composition –– percent of body fat in ratio to muscle density.

To increase buoyancy and ability to float, and reduce drag through water, relax. Tenseness inhibits buoyancy and forward movement. Muscles not being used to accomplish the desired movement should be relaxed. Don’t thrash. Displace more water. Change your breathing pattern. Although rhythmic breathing will promote relaxation for distance swimming, explosive breathing will increase chest volume, spread weight over a greater area, displace more water, and therefore increase buoyancy. Move centers of buoyancy and gravity closer together. Arch your back, put your arms out or behind your head, bring up your legs. Use propulsive movements. Also, if you’re moving forward, you will overcome the force of gravity which tends to cause denser body segments such as the legs to sink.