Click Here to Download Pool Tip #51: Pool Heater Sizing (PDF format, 36KB)

Pool Heater Sizing for Temperature Maintenance

• Find pool surface area (ft²)
• Multiplied by 15 –– a constant that represents the BTUs required to raise water temperature one degree per square foot of surface area, then
• Multiply by the desired increase in water temperature over ambient air temperature (maximum temperature rise)
• This will give you the heater output
• After obtaining the required heater output, divide the heater efficiency rating (Ex. ÷ .82) to determine the heater input needed (I = O ÷ E / O = I × E)

Example:
Surface area: 75′ × 48′ = 3,600 square feet
Desired temperature: 85°:
Max. temperature rise: 35°:
Heater efficiency rating: 82%
Heater output: 3,600 × 15 = 54,000 × 35°: = 1,890,000 BTUs
Required heater input: 1,890,000 ÷ .82 = 2,304,878 BTUs

Pool Heaters – Time Needed to Heat Pool Water

• Determine the number of BTUs needed to raise _____ gallons of pool water from ___°: F to ___°: F.
• Use the formula 1 BTU will raise 1 pound of water 1°: F in 1 hour
• Multiply the volume in gallons by 8.33 (weight of 1 gallon of water) to determine the weight of the water that must be heated.
• Multiply the water weight by the desired temperature rise to determine the number of BTUs needed.
• Divide the BTUs needed by the available heater output in BTUs to find the number of hours it will take to heat the water.

Example:
Water volume: 165,000 gallons
Temperature rise: 35° F
Water weight: 165,000 gallons × 8.33 = 1,374,450 lbs
1,374,450 lbs × 35°: F = 48,105,750 BTUs needed to heat
Heater output: 1,890,000 BTUs
48,105,750 BTUs needed to heat to desired temperature ÷ 1,890,000 BTUs output = 25.4 hours

Download Pool Tip #50: Pool Conversion Factors (PDF format, 70KB)

Download Pool Tip #49: Pool Chemical Adjustments (PDF format, 32KB)

Download Pool Tip #48: Chlorine Generators (PDF format, 23KB)

There is a great deal of misunderstanding surrounding the use of so–called “salt systems” or “salt generators” in the pool industry. Electrolytic cells, or more properly called “chlorine generators”, change non iodized salt or low calcium and magnesium salt – salt pellets like those used in water softeners or for making home–made ice cream, into chlorine gas. Electricity is applied to salt dissolved in water to form hypochlorous acid (the active sanitizing ingredient in chlorine), sodium hypochlorite (liquid chlorine made from chlorine gas and sodium hydroxide), and hydrogen gas.

2NaCl + 3H₂0 + electricity = HOCL + HCL + 2NaOH + H₂

I cannot stress this point enough: chlorine is chlorine whether you buy it or make it on site. There is absolutely nothing different about the chlorine you generate on site at your pool, other than its freshness. You are not sanitizing and oxidizing the water with salt. You are using salt and electricity to make chlorine.

Chlorine can be generated on–site at the pool using either in–line or off–line methods. One pound of chlorine can be produced from approximately 1.67 pounds of salt.

In–Line Generators

In this method, 200 – 500 pounds of salt is added directly to the pool for each ten thousand gallons of water. Pool water is circulated through an electrolytic cell consisting of electrically charged, layered plates. Chlorine gas is produced, as are sodium hydroxide and hydrogen gas. All three products are drawn into the circulation system by venturi, mix with pool water in the return line, and are then introduced into the pool through the return inlets. Excess chlorine generated using this method reverts back to salt in the water to be reused.

Off–Line Generators

There are two common types of off–line chlorine generators, the traditional diaphragm or brine systems, and the MIOX system.

In the traditional brine system, there are two chambers separated by a diaphragm membrane. Electricity is passed through a salt water anode (positive electrode) chamber to a distilled water (negative electrode) cathode chamber . The brine solution is split, the chlorine is freed from the salt and bubbles to the top of the chamber. Current carries the sodium ions through the membrane to the cathode chamber, where they react with distilled water to form sodium hydroxide and hydrogen. The hydrogen gas is vented off into the air, and the chlorine compound is introduced into the pool.

The MIOX system is a variation on off–line chlorine generators. Just like the other methods, salt, water and electricity are used to create sodium hypochlorite (and the manufacturer claims, other chlorine–oxygen species). Chlorine is generated on site from a sodium chloride saltwater brine solution by passing the brine solution through a electrolytic cell. The chlorine and mixed oxidant solution is collected in a bulk storage tank and injected into pool water as needed using a peristaltic or diaphragm pump (chlorinator).

Advantages and Disadvantages

The main advantages of using any method of on–site chlorine generation include knowing that the chlorine compound you are using is full strength, fresh and without contaminants. Additionally, you eliminate the hazards associated with storing and transporting chlorine or chlorine compounds. With the in–line and traditional off–line methods, water treatment costs are low. The manufacturer of MIOX systems (but not independent researchers) also claims: better inactivation of Cryptosporidium than chlorine at same doses, more stable and longer lasting chlorine residual with 1.4 times more oxidizing power than chlorine, that the product does not react to form chloramines so there is a lower THM formation, and that MIOX oxidizes ammonia at doses below breakpoint levels resulting in less need to superchlorinate.

Note:  Contrary to manufacturer’s claims, with all methods of chlorine generation in a warm water, heavily used pool, there will be a rise in combined chlorine. There is no such things as a “good chloramine”, just less objectionable forms. Nuisance residuals in poorly ventilated indoor pools is a concern . Monochloramine reacts with FAC and forms di chloramines and tri chloramines (nitrogen trichloride).

The primary disadvantages of using the in–line method include the fact that the pool water has a slightly salty taste, total dissolved solid (TDS) levels build rapidly, and some pieces of pool circulation and filtration equipment and their components will deteriorate more rapidly. With all the methods, the chlorine generating equipment must be cleaned and maintained regularly to prevent fouling. The equipment used to generate the chlorine is somewhat costly and does take up additional space in the chemical storage room. The systems are complicated and more monitoring of the process and staff training will be required. You will still need to store a back–up sanitizer on the premises since chlorine generation systems cannot always keep up with demand, and for vomit, dead animals or fecal accident emergency clean–up procedures. And with the MIOX system, you may need to soften the water.

My recommendation: Stick with the sodium hypochlorite or calcium chlorine hypochlorite chlorine compound you are already using. Buy fresh chemicals from a reputable distributor. And spend your money on a UV light or ozone secondary water treatment system.

Download Pool Tip #47: Breakpoint Chlorination (PDF format, 26KB)

Chlorine is also used to shock or superchlorinate pool water in order to remove unwanted organic compounds from the water, destroy impurities and dissolved waste products and algae, and break apart the chemical bond that holds chlorine and ammonia and nitrogen together. The point at which this chemical bond is broken is called “breakpoint”. Breakpoint chlorination eliminates chloramines and other reductants which cause an increased chlorine demand.

In order to achieve breakpoint, a quantity of 7.6 molecules of free chlorine are used to break apart each molecule of combined chlorine. Several chemical reactions take place. Chlorine reacts with ammonia (NH3) to form monochloramines (NH2Cl). Free chlorine reacts with monochloramines to form dichloramines (NHCL2). Free chlorine reacts with dichloramines to form trichloramines or nitrogen trichloride (NCl3) and nitrates before the breakpoint is achieved. Nitrogen trichloride forms when the HOCl to nitrogen molecular weight ratio is 12 to 1, and oily, insoluble colloidal particles will appear, cloud the water, migrate toward the water surface, and may be released into the ambient air, further contaminating the natatorium environment.

Reaching the breakpoint is an all–or–nothing reaction. If breakpoint is not reached, the problem will be worse. When the chemical bond with ammonia is broken, free chlorine, nitrogen, water and inorganic chloride (salt) remain.

Superchlorination of pool water should be done periodically, as needed, when the level of chloramines present in the water is greater than 0.2 ppm. Products used for superchlorination include chlorine in any form, however, stabilized chlorine products, or isocyanurates (trichlor or dichlor), should not be used for superchlorination since excess cyanuric acid would be added to the water solution concurrently.

Before attempting breakpoint chlorination, lower the pH to 7.2 to 7.4 to increase the percentage of hypochlorous acid which forms, and make sure the water is chemically balanced. Shocking a pool with unbalanced water, particularly with a high (basic) pH or high total alkalinity, will result in the formation of a white carbonate precipitate which will cloud the water. However, some operators prefer to raise the pH when using acidic chlorine products like elemental gas chlorine for superchlorination since more offensive forms of chloramines develop rapidly at a very low pH.

To calculate breakpoint in order to superchlorinate, use a DPD (N,N–diethyl–p–phenelynediamine) or FAS (ferrous ammonium sulfate) test kit to find both the free and total available chlorine levels. Subtract the free available chlorine (FAC) from the total available chlorine (TAC) to find the combined available chlorine (CAC) level. Multiply the CAC by the factor 10, although only 7.6 is actually needed, to find the dose of chlorine you must introduce into the pool in order to reach the breakpoint. Ten is used as a factor because most pool operators are not sure of the precise amount of water in their pools, or of the exact percentage of available chlorine in the chlorine compound being used. We use ten as a factor to err on the side of caution and so that enough chlorine is left over after breakpoint has been achieved to satisfy the chlorine demand and leave an adequate residual.

Determine the number of gallons of pool water to be treated and the percentage of available chlorine in the product that will be used to superchlorinate the pool. Calculate the amount of chlorine needed by weight, or refer to a standard chart or a chart provided by the chlorine manufacturer.

For example: If free available chlorine is 1.0 ppm and total available chlorine is 1.5 ppm, the difference (combined available chlorine) is 0.5 ppm. Multiply 0.5 by 10 to determine that 5 ppm of chlorine must be added to the water in order to reach breakpoint. You know that the pool in question contains 25,000 gallons of water, and you plan to superchlorinate using 10% available sodium hypochlorite. By following the chart and inserting the appropriate numbers into the formula, you can determine that 1 gallon of 12% sodium hypochlorite must be added to a 25,000 gallon pool, to eliminate 0.5 ppm of combined chlorine.

(1.5 cups) (1 ppm) (10,000 gallons)
(1.3 cups) (5 ppm) (2.5) = 16.25 cups ÷ 16 = 1 gallon

Some health department regulations may prohibit swimmers from using the pool when chlorine concentrations are elevated. It is best to superchlorinate in the evening or during hours the pool is not in operation to avoid respiratory irritation to users from off gassing during the superchlorination process, and to allow chlorine levels to drop back to normal levels. How fast breakpoint is reached depends on several factors, including: pH, pool water temperature, the ratio of free available chlorine to combined chlorine, and the concentration of ammonia/nitrogen and organic nitrogen compounds which place a demand on the chlorine. If the chemical reaction takes place and breakpoint is reached, the large amounts of chlorine added to the water will be used up in the process. Free chlorine will return to normal operating levels, and the combined chlorines will be eliminated.

Download Pool Tip #46: Accident Reports (PDF format, 29KB)

If you perform a water rescue or supply first aid, regardless of how minor the incident or injury seems at the time, it is import that you document what you did to assist the patron. Your follow–up to an accident should include writing a complete and accurate report of the facts of the incident. This will help protect you and the facility owner should the injured patron file a claim for damages.

While treating an accident victim, express sorrow, but not feelings of anger or guilt about what happened. Be careful not to imply fault. Do not make any statement to assume liability, or make patrons believe the facility or personnel are in any way liable for what happened.

Immediately after the emergency is under control, gather as much information as possible about what happened so that EMTs can pass the information on to the hospital emergency room staff after transporting the victim for medical care. Find out what hospital the victim is being taken to. Notify relatives of the accident victim that an accident occurred. If transportation to the hospital or follow–up care was not warranted, the victim should be asked to sign a statement that first aid was given and he was released into his own care or the care of his parents or another responsible party.

Conduct a complete investigation into the incident. A thorough evaluation may help prevent a similar incident in the future. Gather additional information about the accident, employee involvement, and the condition of the facility at the time of the accident. Take photographs of the accident site. Record the date and time, if possible, on the photo. Make a diagram of the pool area. Record how many people were on the premises. Collect the daily pool chemical and maintenance logs, and information on the condition of the facility at the time of the incident. Gather personnel records, work schedules, and pertinent in–service training and auditing records for any employees who were involved in the rescue or follow–up care given to the patron. Obtain written statements from employees and credible witnesses. Fill out an accident or incident report.

Remember to report the accident and notify all parties, including: the facility’s insurance carrier, the facility’s attorney, your supervisor and all individuals in the chain of liability. Serious accidents may need to be reported to the authorities, and to the state or county health department.

Properly completing accident and incident reports can help reduce liability. Do not speculate about the cause of the accident, or how the accident could have been prevented, and, certainly don’t record this information on the accident report. Do not discuss the accident among employees of the pool as a group, and then write a joint statement. These statements often sound as if the employees got together to get their story straight and cover up their involvement or responsibility for what happened. Do not describe events in the first person if you are relating what someone else told you. Designate one individual to provide information to patrons and the media. Prepare a statement and refrain from discussing the events with curious patrons or the press.

Ask witnesses to hand write, in their own words, sign and date an account of what happened and what they observed. Have witnesses relate step–by–step what occurred from their point of view –– where they were, and what they were doing. Written statements from witnesses should be witnessed by someone else who was not directly involved in the accident and not an employee or relative or close friend of the victim. Interview witnesses individually. Tape the interview if possible. Make sure the witness knows the interview is being tape recorded, and obtain the person’s permission to record while on the tape.

If possible, obtain a statement from the injured party. Ask the injured patron to be as descriptive, detailed and as exact as possible about what happened. Ask questions about the incident. Ask the injured patron if they were at fault or somehow were even partially responsible for what happened. Later after having had time to think about the event or discuss it with friends or their attorney, they’ll be less likely to admit fault. Write down exactly what the patron says. Tape the interview if possible and with the victim’s knowledge and permission. Ask the injured patron to read and sign the statement.

Call the injured party 24 to 48 hours later. Show concern, discover the extent of the injury, and the injured patron’s attitude or feeling about what happened and the responsibility of facility. Document the call and any information obtained.

Accident report forms should be retained indefinitely. Although there is usually a statute of limitations of 1 to 3 years for filing a complaint against a defendant facility, an accident report should not be destroyed at the end of that period of time. The courts have permitted individuals who were not aware of the extent of their injuries, or who have had injuries which were not discoverable within the period of limitations to file a complaint at a later date. Also, in most states, for accidents involving minors, children have a right to start legal proceedings as late as 2 to 4 years after they reach the age of 18, regardless of when the injury occurred.

Download Pool Tip #45: Calling for Help in an Emergency (PDF format, 20KB)

If it is safe to leave the accident victim briefly, or if no one else is around to place the phone call, activate the emergency medical system (EMS) by dialing 911 from any phone. In some areas of the country still not connected to an emergency network, you may need to dial “0” or a regular seven digit phone number in order to obtain emergency service. In some facilities, it may be necessary to first dial “9” or some other number in order to reach an outside line.

An emergency telephone should be installed in the pool area. Or, at least one regular telephone line should be dedicated for emergency use only. It is not necessary to deposit coins when dialing 911 from a pay phone.

Instructions regarding emergency calls should be prominently posted next to the phone, including phone numbers of the nearest fire, police, hospital, physician, and emergency services provider, along with the address and phone number of the facility, directions to the facility and other pertinent information to be conveyed to the 911 operator.

When you reach the emergency operator, tell her who you are and the phone number you’re calling from. Give the operator the name of the facility and the street address of the pool. Give accurate directions to the facility and mention cross streets and nearby landmarks that might help emergency personnel find the facility.

Describe what happened. Describe the victim’s condition and what first aid is being provided. Make sure you mention if more than one person is injured.

Do not hang up the phone. The operator may need more information, better directions, or may want to convey information from medical personnel. Let the operator know if you are the only person available to speak on the phone, and you must get back to the victim to provide additional first aid.

Download Pool Tip #44: Calling for Help in an Emergency (PDF format, 30KB)

Examine the accident scene and make sure it is safe to proceed with the rescue

Primary rescuer:

• Signal the emergency to notify staff that you are leaving your designated post to provide rescue assistance
• Enter the water (if necessary), and approach the injured victim
• Perform the rescue and manage the situation within 20 seconds
• Bring the injured patron to the pre arranged point on the deck, or if the patron is not in physical danger and cannot be moved, bring the first aid equipment to the victim
• Provide emergency first aid treatment until relieved by paramedical authorities

Additional rescuers:

• Notify emergency EMS and supervisory personnel that an accident has occurred and that assistance is needed
• Send someone to meet the emergency vehicle and direct EMTs to the accident scene
• Clear the pool and move all patrons away from the impact zone
• Provide crowd control
• Direct relatives or friends of the victim away from the accident site; provide comfort and assurance that the victim is being properly cared for
• Bring first aid kits or other needed rescue equipment to the pre–arranged point on the pool deck
• Remove all hazards that might hinder the rescue attempt
• Identify the victim and notify parents if the injured patron is a minor
• Gather as much information as possible about what happened so that emergency personnel can pass the information on to the hospital emergency room staff after transporting the victim for medical care
• Find out what hospital the victim is being taken to
• Immediately after the incident, conduct a thorough investigation into the incident, gather additional information about the accident, staff involvement, and condition of the facility at the time of the accident
• Ask witnesses to hand write (in their own words), sign and date an account of what happened and what they observed
• Complete an accident report
• Contact the facility’s insurance carrier or attorney
• Designate one individual to provide information to patrons and the media.

REMEMBER:

Always check for possible spinal injury before making a water rescue.

Treat life threatening emergencies first:

Non breathing and cardiac emergencies
Severe bleeding
Poisoning

Before responding, always look around and make sure it is safe for you to perform the rescue. Do not endanger your life, or the lives of others by responding to a situation which is dangerous or beyond your training or ability to handle alone.

When you reach the victim, bring his head above the surface of the water. Assess the victim’s condition by conducting a “primary survey”. Check to see whether the victim is conscious and breathing, and has a pulse. Call for help or direct someone else to activate the Emergency Medical System by calling 911. If needed, start resuscitation efforts in the pool, or remove the victim from the water. Do whatever is necessary to prevent further injury to the victim. Treat for shock.

Try to determine what happened. If the victim is conscious and coherent, ask him to describe the events that led to his injuries. If there are witnesses to the incident, ask them to describe what they observed. Examine the accident scene for clues as to what transpired.

Monitor the victim’s vital signs, and perform a “secondary survey” to look for other injuries the victim may have sustained. Provide appropriate first aid, remembering to take universal precautions, and use appropriate personal protective gear.

Download Pool Tip #43: Langelier Saturation Index (PDF format, 30KB)

Monitor the water balance in the pools (weekly) and spas and wading pools (daily) for mineral saturation control. Since water is the universal solvent, all things will inevitably dissolve in water until the water becomes saturated. Eventually, water will become oversaturated, and excess products will be lost by precipitation. Well balanced water will increase bather comfort and will dramatically extend the life expectancy of the pool and its components.

Water temperature, pH, total alkalinity, calcium hardness, and total dissolved solids act together to cause corrosiveness or calcification qualities of water. The Langelier Saturation Index formula and chart can be used to determine if pool water is balanced –– that is, neither aggressive nor oversaturated.

SI = pH + alkalinity factor + calcium hardness factor + temperature factor – TDS factor

Saturation index equals pH plus the alkalinity factor, plus the calcium hardness factor plus the temperature factor minus the TDS factor.

Use your test kit and testing instruments to find each of the five values. Write down the actual pH value found. Then for the remaining four values, find the corresponding factor on the chart. Add or subtract the factors to or from the pH value. If an actual value is not found on the saturation index chart, do not interpolate –– there is no direct linear relationship between the values. Rather, move to the next higher value and use its factor.

If the sum obtained is zero, the water is balanced and chemical equilibrium has been achieved. A tolerance of plus or minus 0.3 is allowable for commercial swimming pools. Negative values indicate corrosive water, while positive values indicate likely calcification and scale formation.

Corrosive or under saturated water is aggressive and will cause circulation pipes, heater elements, and other metal components of the pool to corrode. Pool wall surface materials will deteriorate. Plaster will soften and etch, metal staining will increase, and tiles will become loose and begin popping off the walls.

If the water is oversaturated, calcium carbonate will begin to settle out of the water. Water will become cloudy and take on a “milky” appearance. Scale will build up on solid surfaces, making the surfaces rough, and discoloring dark colored surfaces. Calcium carbonate scale will also build up on the interior surfaces of the pool recirculation pipes. Water flow will be restricted and pressure will increase. Sanitizer effectiveness will be reduced, and algae growth may increase.

If the saturation index formula indicates that the pool water is not balanced (not equal to zero, plus or minus 0.3), make the appropriate chemical corrections, starting with total alkalinity, then followed by pH, temperature, calcium hardness, and TDS.

Example:

SI = pH +af + cf + tf – TDSf

SI = 7.7 + 2.2 + 2.1 + .9 – 12.1 = +.8

*  If cyanuric acid level are high, divide the cyanuric acid level by 3, then subtract this interference factor from the total alkalinity reading prior to calculating the saturation index.

Download Pool Tip #42a: Fecal Accident Log (PDF format, 25KB)