Archive for November, 2009

The Swimming Pool Operators and Owners Resources Pages

Resource Page 1Installation Standards & Recommendations

Items on This Page

  • Pool Turnover Periods
  • Bather Loads
  • Water Chemistry Testing
  • Microbiological Water Testing
  • Water Temperatures
  • Water Heating
  • Sump Grill
  • Skimmers
  • Side Suctions
  • Inlets
  • Level Deck Pools
  • Balance Tanks
  • Pipe Classes
  • Water Velocity in Pipes
  • Filtration
  • Chemical Safety
  • Electrical Safety
  • Gas Safety

There are a number of accepted Standards and Recommendations covering almost every aspect of swimming pool design and consruction. Of course, the Standards and Recommendations for commercial pools are similar to those for the private home pools, but the heavy use that commercial pools endure means that some aspects are different.

The Standards and Recommendations which we discuss here apply to the circulation and filtration design etc., and are the ones we apply to all our Design and Specification work.


Pool TURNOVER Period

This is the theoretical time taken for the total pool volume to pass through the filtration system once.

Example:- Pool Volume = 25,000 gallons. The circulation pump output is 5,000 gallons per hour. 25,000 divided by 5,000 = 5. The Pool Turnover Period is 5 hours, and the Pool Turnover Rate is 5,000 gallons per hour.

(It has been proved that at least 7 complete turnover periods are needed before 99% of the pool water has actually passed through the filters.)

Recommended Pool Turnover Periods

  • Leisure Water Bubble Pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 – 20 Minutes
  • Teaching Pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 – 1 hour
  • Waterslide Splash Pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 – 1 hour
  • Leisure Waters up to 0.5m deep . . . . . . . . . . . . . . . . . . . . . . . . . . . .Max 0.5 hour
  • Leisure Water 0.5m to 1m deep . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.5 – 1 hour
  • Leisure Waters 1m to 1.5m deep . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 – 1.5 hours
  • Leisure Pools over 1.5m deep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 – 2.5 hours
  • Conventional Pools up to 25m long with a 1m shallow end . . . 2.5 – 3 hours
  • Competition Pools 50m long and 2m deep . . . . . . . . . . . . . . . . . . 3 – 4.5 hours
  • Diving Pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 – 6 hours
  • Residential or Private pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 – 6 hours

Maximum Bathing Loads

There are two distinct sets of conditions to determine the Maximum Bathing Load. Maximum SAFE bather load, and Maximum DESIGN Bather Load

Maximum SAFE Bathing Load is simply determined from the surface area of the pool, and is the maximum number of bathers who can SAFELY be allowed to use a facility of a given surface area. The depth of water also influences this figure since it has been determined that shallow water can safely support more bathers than deep water. If the SAFE Bather Load is exceeded, it is considered that there will be an unacceptable risk of accidents due to bather collisions, or drownings etc, and that lifeguarding will be impared due to reduced visability to below water level by lifeguards.

The Maximum SAFE Bather load.

  • Shallow Water (under 1m deep) . . . . . 1 bather per 2.2 square metres – (23.7 square feet)
  • Standing Water (1 – 1.5 m deep) . . . . . .1 bather per 2.7 square metres – (29 square feet)
  • Deep Water (over 1.5 m deep) . . . . . . .1 bather per 4 square metres – (43 square feet)
  • Very Deep Water (over 2 m deep) . . . 1 bather per 4 square metres OR Maximum DESIGN Bather load – (whichever is less)

Please Note:- When determining which formula applies to your pool you must take the deepest depth of the pool. Example: A pool has a shallow end depth of 0.8 metres and a deep end depth of 1.8 metres – you must use the formula “Deep Water (over 1.5m deep)” to determine that pool’s Safe Bather load.


The Maximum DESIGN Bather load.

The Maximum DESIGN Bathing Load is the number of bathers per Hour that the circulation and filtration equipment can successfully support without losing water quality. This means that the pool water will not begin to get cloudy through excessive dirt and debris, and the Free Chlorine level and pH value will remain within acceptable limits throughout the entire pool.

  • The Maximum DESIGN Bather Load = Pool Circulation Rate (in cubic metres per hour) divided by 1.7

Warning Note:- For example, a teaching pool running 3 x 20 minute sessions per hour with each session comprising of 10 bathers – Just because each session with 10 bathers only lasts 20 minutes this does NOT mean 10 bathers per hour as is sometimes interpreted by swimming teachers attempting to over utilise their pool. It means 30 bathers per hour!


Carrying out MANUAL Testing the pool water is a very important part of the regular “Pool Mainrtenance”. It cannot be stressed too strongly that REGULAR, FREQUENT and ACCURATE manual water chemistry tests are essential. The Principle Tests are for pH and Disinfection. Additional tests may be needed for the assesment of residual chemicals. There are further details on Page 9 – Water Tesing and Analysis.

Swimming Pool operators have a legal resposibility to provide a SAFE environment not only for their staff but for the public and any other person who may be on their premises. This responsibility extends to positive knowledge that the swimming pool water chemistry is unlikely to affect the health of any person in or near to the water. This is a Legal “Duty of Care”

Before any pool is opened or made available for use, the Pool Owner or Pool Operator must be satisfied that the water quality is safe for bather use. In the School, Hotel, and Leisure Pool environment this means that the pool water MUST be tested by a competent person using an approved Water Tesing Kit – BEFORE any person is allowed into the pool facility. There must also be some means of positivily confirming that the testing has been carried out – i.e. test results, and a signature in the “OK to Use” column in the pool record book. School pools especially, often suffer from negligence with respect to water testing. Certainly, it is not sufficient for a school swimming instructor to unlock the pool for a class to use because “I wasn’t told there was anything wrong” In a case like this the Swimming Instructor could be held liable for negligence because they had not taken “Reasonable Care” to ensure the water was safe.

The pool water chemistry must be regularly tested by a competent person using a suitable Manual Test Kit throughout the time that the pool is available for use. The frequencey of manual testing will depend on (a) whether or not there is any form of automatic or semi-automatic chemical control, (b) the volume of the pool, and (c) the type of use. Typicall,y manual Testing will take place every two or three hours whilst the pool is in use. If the chemical levels are controlled by “hand-dosing” and the pool is busy, testing every hour may be more appropriate.

At the end of the day, the pool should always be tested again before closing up for the night. This will allow any last minute corrections to be achieved so that there will not be a failure of disinfection overnight – during the “recovery period” of the pool. This is important since any overnight failures will usually cause a delay in allowing the pool open for use the next morning.


Since microbiological analysis is usually undertaken away from the pool and it will normally take at least 24 hours before any results are available, the microbiological safety is “Asumptive” – i.e – PROVIDED the pool Disinfection and pH has not failed and has remained constantly above the accepted minimum values, – it can be assumed (short term) that the microbiological quality of the water is satisfactory and safe. This does not however, absolve the Pool Operator of undertaking regular actual microbiological testing. Most commercial pools should have regular microbiological testing at a suitable frequency anywhere between 4 and 26 times per year. Often, a simple Plate Count or TVC will be sufficient, with further investigation and more specific testing if these initial tests show a significant presence of bacteria.


Pool Water Temperature

Recommended Maximum Pool Water Temperatures

  • Competitive swimming & diving, Fitness swimming, Training . . 27 deg C – (80.6 deg F)
  • Recreational, Adult teaching, Conventional main pools . . . . . . . 28 deg C – (82.4 deg F)
  • Childrens teaching, Leisure pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 deg C – (84.2 deg F)
  • Babies, Young children, Disabled & handicapped. . . . . . . . . . . . .30 deg C – (86.0 deg F)
  • The Pool Hall should always be 1 deg C ( 2 deg F) above water temperature at 55% – 65% RH. (Except hot water & Hydrotherapy Pools)

    • Generally, outdoor pools will usually operate at the same or a lower temperature than their indoor equivalents.

    High water temperatures are usually unnecessary and may cause damage or reduce the life span of many items of pool equipment. Liners may lose their elasticity, – pool covers will have a reduced life, – plastic fittings may become brittle and break, – filter underdrains or laterals may become distorted or damaged, – socket unions may loose their shape and leak, – water valves may fail or break, – plastic pipework may become distorted, – excessive evaporation may be lost from the water, – heating costs may be excessively high, – chemical consumption will usually increase, and microbiological activity will increase.

    Concrete Pools

    • The Maximum Heating Rate or Temperature Rise (or fall) for a concrete built pool is 1 deg F per hour ( 1 deg C per 2 hours)
    • Big commercial concrete pools and similar structures will often have a maximum temperature rise (or fall) of 1 deg F per 2 hours ( 1 deg C per 4 hours).

    Exceeding the maximum temperature rise can cause cracks, fractures and leaks in the pool structure due to unequal thermal expansion of the shell etc.

    Probably the worst shock for a pool shell is warm water being drained, and the pool immediately fast filled with cold water. This sort of action can cause terminal and often unrepairable damage to the structure.

    Liner Pools

    Although most liner type pools can enjoy a brisk temperature rise, most manufacturers of vinyl pool liners do not really recommend the water temperature to exceed about 85 deg F (29.4 deg C). If the recommended pool temperatures listed above are followed, this should not be a problem.

    High water temperatures can cause vinyl liners to expand and loose their elastic properties causing wrinkles and creases to appear which are usually impossible to remove. High temperatures can also destroy the oils and polymers in the material, so that the liner rapidly becomes brittle and susceptable to damage. Delamination of the various layers in the vinyl material construction also frequently occurs.

    Some manufactures do produce pool liners which are designed for higher temperatures. However, the manufacturers instructions and conditions must be closely adhered to if damage is to be avoided.

    Direct Heating Gas Heaters

    Direct heating gas and oil heaters should always be installed with a “Delay Off” timer inter-connected between the heater and the circulation pump. This ensures that when the circulation pump is normally “switched off”, the heater is automaticaly switched off straight away, but the circulation pump continues running for between 10 and 30 minutes (depending on the size of heater). This ensures that the circulation pump is not stopped while the heater is still hot.

    Considerable damage can be caused to Direct Gas Heaters if the circulation water suddenly stops, particularly if the heater was actually fired up and running at the time of the pump being stopped.

    It is essential that all Direct Gas Heaters are switched off for at least 10 – 30 minutes (depending on heater size) before the the circulation pump is stopped


    Number of Sump Grills.

    There must always be a minimum of 2 sump drains, at least 2 metres apart, in every pool. All sump drains must be directly connected to each other so that there can never be the possibility of only one suction point in operation. In practise this means that all the sum drains are interconnected in the base of the pool to one sump suction pipe which is routed to the plantroom. There have been too many accidents where swimmers (both adults and children) have been seriously injured or drowned through being caught against a single sump grill.

    Maximum Proportion of Water Through the Sump.

    • Normal leisure and home pools – 30%
    • Teaching and Childrens Pools – 20%
    • Hydrotherapy and other hot pools – 10%

    The surface of the pool water is usually the most polluted part, with body oils and grease, sweat, skin debris and other pollutants usually within the top 6 inches. It is therefore essential that there is good surface skimming by either enough Skimmer units built into the pool shell, or by Level Deck surface skimming so that at least 70% of the pool water is drawn from the pool surface for filtration and treatment.

    Velocity of Water Through the Sump Grills.

    • Water less than 1 metre deep – Max velocity 1/2 ft per second
    • Water 1 – 1.5 metres deep – Max velocity 1ft per second
    • Water greater than 1.5 metres deep – Max velocity 1.5 ft per second

    It is an essential safety aspect that the water velocity through the sump grills is never likely to cause danger to any pool users.

    The number of sumps required must be calculated on the basis of 100% sump suction, since there may be times when the pool is in use with the surface draw-off not operating. It is essential that these figures are calculated, and not simply guessed.


    The recommended ideal flowrate through a conventional skimmer is usually about 5 cubic metres per hour – about 1,100 imperial gallons per hour. The absolute maximum acceptable flowrate is around 7.5 cubic metres per hour – about 1650 imperial gallons per hour – based on standard swimming pool skimmers – NOT the small spa skimmers.

    Since most of the pollutants are found at the water surface of the pool or spa. it is essential that there is a high percantage of surface skimming, especially on warmer pools where there is more body oil and grease lost to the water..

    The correct installation of a skimmer for a commercial pool is shown below. The Balance Pipe ensure that water will still flow into the skimmer suction if the level has dropped below the skimmer mouth, – after backwashing, for instance, and this avoids the dangerous use of 100% suction through the sump drains.

    Water enters the Balance Pipe via an adjustable inlet fitting, and this is adjusted to provide just enough water to keep the suction flooded when the water depth is at the lowest expected level after a good filter backwash. Once the water level is raised to the skimmer mouth, almost all the water takes the line of least resistance and flows into the skimmer via the skimmer mouth.

    It is essential that ALL the skimmers at a pool are installed the same way. Intalling only a few Skimmers with Balance Pipes will still result in the suction pulling air from the other skimmers – and a loss of prime to the pump.

    Please wait while the drawing of a skimmer installation is loaded.

    Balance Pipes can be omitted on lightly used residential pools in some circumstances. For instance, pool installers or often reluctant to have any more skin fitting on a domestic liner pool than is absolutely necessary, because each perforation of the liner is a potential for leaks.

    By definition, Skimmers are constantly drawing the surface water where all the body oils and grease is present, and it is essential that regular waterline cleaning includes the scum line inside the skimmer body as well as the pool shell scumline.


    Side Suction Fittings

    The usage of side suction fittings, especially when attempting to “upgrade the circulation” of a swimming pool is extremely dangerous and should be avoided at all costs. Water velocities at side suctions are frequently exccesively high and the position of them makes hair entrapment very likely.

    In order to “Upgrade” the circulation of a swimming pool it is far safer and far more useful to install extra skimmers.

    Inlet Water Velocity

    Section Under Construction and will be uploaded soon

    Level Deck Overflow Channels

    The Level Deck Drainage Channels should be capable of holding 125% of the Surge Dispalcement volume

    The drainage pipes from the overflow channel to the Balance Tank should be capapble of delivering 125% of the maximum total pool turnover rate into the Balance Tank.


    Level Deck Balance Tanks

    The Level Deck Pool Balance Tank should be capable of taking the Total Displacement of the Maximum Design Bather Load or the Maximum Safe Bather Load – whichever is the greater. There should also be a provision for surge values (splashover), and this volume will be determined by the type of pool and use it will receive when busy.

    It is important to remember that EVERY pool will generate a “Scum Line” of body grease and dirt at the waterline. In the case of a Level Deck pool, this Scum Line will be concentrated on the Balance Tank walls, and must be frequently and regularly removed and cleaned.

    Balance Tanks are an extension of the pool itself, and must be treated as such –

    • The Tank Shell Finish should be smooth to facilitate easy cleaning – ideally finished with large white tiles.
    • Access to the inside of the Balance Tank should be easy and quick – to encourage regular inspections and cleaning.
    • The Balance tank should be able to be easily drained, and have sufficient headroom inside to allow regular inspection and cleaning.
    • For safety reasons there should never be more than 3m of ceiling space without an access point in the Balance Tank – i.e. an operative inside the balance tank is never more than 1.5m from an access hatchway.

    Automatic Water Top-Up

    The Automatic Top-Up unit installed at the side of the pool usually consists of a recess connected to the pool water via a 1.5″ pipe – so the water level inside the unit is the same as that in the pool. A float valve arrangement controls the flow of water into the unit to top-up the pool water.

    It is essential that the Mains Water Supply is not connected directly to the Auto Top-Up unit.

    Serious contamination of the mains water could occur if the mains supply pressure was to drop for any reason, and pool water was drawn into the supply pipe.

    A suitable “Break-Tank” should always be installed at a convienient location (usually the Plant Room). Here, the water level in the Break Tank is controlled by a float valve connected to the incoming mains water supply. The water in the break tank is gravity fed to the float valve in the automatic top-up unit adjacent to the pool.


    Pipe Materials and Class (wall thickness)

    The pipework used for swimming pools circulation systems is normally classified by its wall thickness and wall strength. The wall thickness varies according to the pipe diameter. It must be remembered that the controlled size is the external diameter, since this has to accurately fit inside a wide range of pipe connections. Most plastic pipework for swimming pool use is either PVC or ABS. The most common class used (particularly for domestic pools) is Class C.

    Class D pipe has a slightly thicker wall than Class C, and Class E is even thicker. Class T is the thickest walled pipe, and the wall is thick enough for threads to be cut directly into the plastic.

    ABS pipe tends to resist shattering a little more than PVC, so ABS Class D or Class E pipe is often specified where the pipework is to be buried below ground, or under flooring etc.

    Water Velocity in Pipework

    The velocity of water within a pipe is subjected to physical resistance due to friction and turbulance. This can easily be demonstrated with a long garden hosepipe. Although the water may gush rapidly out of the tap or standpipe, by the time it comes out of the hose at the other end the velocity will have significantly slowed. The same occurs in swimming pool pipework, and all pipe installations must have the pipe sizes calculated in order for the water volume delivered through the pipe is not too high for the pipe diameter.

    • The maximum velocity in any suction pipe must not exceed 5 feet per second (1.52 metres per second).
    • The maximum velocity in any pressure pipe must not exceed 9 feet per second (2.74 metres per second).

    On large commercial installations, the circulation pumps will frequently have much smaller pipe flange couplings than the pipe work connecting to them. On these installations, conical pipe adaptors are often fitted each side of the pump to allow a smooth transition from the very high velocity found within the pump to the relatively slow velocity required within the pipework.



    Filtration Rate

    The Filtration Rate is the speed or velocity of the water through the filtration media. The slower the Filtration Rate – the more effective the filtration.

    • Big or heavily used commercial pools will normaly use LOW filtration Rates.
    • Schools, hotels, other commercial pools, and heavily used private pools will usually have a MEDIUM fitration rate.
    • HIGH rate filtration is usually only suitable for private home pools,

    The Filtration Rate is measured in Cubic metres of water per Square metre of Filter Surface Area per Hour – ( CuMtrs/SqrMtr/Hr or m3/m2/hr )

    OR Gallons per Square Foot of Filter Surface Area per Hour- ( Gall/SqFt/Hr or gal/ft2/hr

    Filtration Rates for Sand Filters (Metric rates)

    • LOW RATE FILTRATION – Less than 10 m3/m2/hr
    • MEDIUM RATE FILTRATION –11 m3/m2/hr to 30 m3m2/hr
    • HIGH RATE FILTRATION – 31 m3/m2/hr to 50 m3/m2/hr

    (NOTE : – Many Sand Filters have a maximum Filtration Rate of 45 m3/m2/hr)

    Filtration Rates for Sand Filters (Imperial Rates)

    • LOW RATE FILTRATION – 200 gal/ft2/hr or less
    • MEDIUM RATE FILTRATION – Above 200 gal/ft2/hr to 600 ga/ft2/hr
    • HIGH RATE FILTRATION – Above 600 gal/ft2/hr to 1000 gal/ft2/hr

    Please note:- It is important that the maximum filtration rate determined by the filter manufacturer is not exceed. Excessively high filtration rates will cause debris to be “stripped through” the filtration media, and distortion and damage to the filter underdrains. Too many Pool Installers still do not calculate filtration velocities and simply guess. They are not helped by unscrupulous equipment distributors who offer mismatched pump and filter kits in their catalogs. It cannot be too strongly emphasised that correctly designing an efficient and effective swimming pool circulation & filtration system involves performing a lot of calculations.


    Backwashing the Filters

    There are THREE criteria for prompting filter backwashing :-

    1. Each filter must be backwashed at least ONCE per WEEK
    2. Each filter must be backwashed when the pressure gauges indicate a pressure RISE of around 3 lbs sq inch.
    3. Filter backwashing will be prompted in order that sufficient topping up with fresh water follows so that one or more residual chemicals are controlled by dilution. (NB – Residual control could be achieved by simply dumping water, however it is a more efficient use of resources to use the water to clean the filters while discardeding it.)
    • In the absence of residual testing, all commercially operated pools should dump at least 10% of the pool volume per week.
    • European recommendations are that 30 litres of pool water per bather per day is replaced with fresh.

    Please note:- A number of distribuors and manufacturers make claims that their “equipment of product reduces the need to backwash” ! It must be remembered that cleaning the filters is only part of the Backwash function. Replacement of water in a swimming pool is essential for controlling undesirable residual chemicals which will otherwise build up in the water. Claims by manufacturers of “add-on” equipment that in some instance, they claim reduces the nead to backwash by up to 80% do NOT take into account residual and trace chemicals which can ONLY be controlled by dilution. Likewise, one equipment distributor has suggested that in order to save water the backwash effluant is passed through a cartridge filter “supplied by them”, of course and then this filtered water is returned back to the pool. Although this was suggested for residential pools, there was no thought on how the various chemical residuals remaining in the water would be controlled.

    Any reduction in poolwater replacement MUST be accompanied by careful monitoring of all the residuals to ensure that dangerously high levels are not allowed to develop.

    Filter Media

    The filter media in a normal leisure pool sand filter should be checked at least once per year. This is achieved by opening the filter and examining the media. Any signs of contamination should prompt a media change.

    Hot water pools such as Teaching Pools, Hydrotherapy Pools, and Spas should have the filter media checked about every 3 months.

    Electrical Safety

    In the UK the electrical installation rules and regulations are provided by the Institution of Electrical Engineers. These regulations are enforcable, and failure to observe them could result in severe penalties. The current rules are all published in the IEE Regulations. We consider it is essential that any person contemplating carrying out any electrical repairs or installations within the UK, has a copy of this publication to ensure that all the electrical activities are carried out to an approved manner and standard.

    One of the most important recent regulations is the creation of the “Zone” system of regulations. Three Zones are created, – Zone A is within the pool shell, – Zone B is an area extending 2 metres from the edge of the pool and a height of 2.5 metres above the highest part of the pool, – Zone C is an extension of Zone B for a further 1.5 metres.

    In essence, no electrical equipment is allowed inside Zone A or Zone B unless it is “SELV” (Safe Electrical Low Voltage) of not more than 12 volts (i.e. – underwater lights)

    Another regulation often ignored is the provision of equipotential bonding on all electrically conductive equipment. This implies that all ladders and handrails etc. must be electrically joined and earthed to all other all other metalic equipment in the vicinity.

    We understand that if a recent regulation creates a situation where an older installation of electrical equipment would now be illegal, – unless that installation is believed dangerous the owner would not be forced to carry out remedial work to conform to the current regulations. However, any repairs or replacements to that equipment would be illegal and the engineer would be just as liable as if he had carried out the illegal installion in full after the regulation came into force.

    Gas Safety

    In the UK, by Law, all businesses installing or servicing gas appliances MUST be registered with GAS SAFE. Any person working on a gas appliance must be recognised and approved by GAS SAFE. There are heavy fines for persons not registered with GAS SAFE and found working on gas appliances.

    One of the most important aspects of gas heater installation is the provision of sufficient air to enable the combustion to take place correctly. If the gas heater is not supplied with enough air, – Carbon Monoxide will be produced in large quantities, and this odourless gas quickly KILLS.

    Even a relatively small swimming pool gas heater can require quite large wall ventilator openings, correctly positioned.

    Gas heaters should be serviced every year (ideally in the spring) by a Qualified and Registered GAS SAFE Engineer who is fully familiar with swimming pool gas heaters.


    Section Under Construction and will be uploaded soon


    From USA Swimming

    Prevention of the Chloramine Problem
    The most common methods are:

    • Change the air circulation system settings to include more fresh air introduction and better turnover.
    • Evaluate the type and brands of chemicals being used to treat the pool water for both chlorine and pH control.
    • Evaluate the pool filtration system to see if a filter that filters down to a more effective micron rating would be effective.
    • Check the labels on all cleaning products to make sure they do not contain ammonia and are not nitrogen enriched.
    • Require showers before entering the pool. Showers are usually required by state health codes.
    • In warmer months consider aerating at night with a booster pump and spay nozzle.
    • Consider installing an Ultra Violet (UV) water treatment system that cuts down on the amount of chlorine used and also “breaks down” chloramines. (See information at end of this article about UV)

    Changing the Pool Water
    When does the pool water need to be changed. That depends on:

    • The size of the pool
    • The water temperatureThe bather load
    • The type and brand of chemicals used
    • The type of filter and the turnover rate

    In general the smaller the pool the more frequently the water has to be changed.  Hot Tubs in the 300-600 gallon range need to be drained and refilled at least monthly. Many health departments require that exact schedule.

    Many specialty pools, such as lessons pools or therapy pools in the 1,500 to 5,000 gallon range need to be drained every three to four months.  The warmer the water and the higher the bather load the more frequently the water needs to be changed.

    Larger pools, such as lap pools and competitive pools can actually go years before draining. Because of the large surface area of these pools exposed to evaporation, new water is constantly being added. In effect the water is always in a state of renewal. There are pools with perfect water that have not been drained for four years or more.

    Some things that can shorten the life of the water and necessitate early draining:

    • Improper chemicals with non-soluble buffers or binders and poorly designed “inert ingredients”
    • Poor quality filtration
    • Continually shocking the pool to break up chloramines
    • Users not taking showers before entering pool

    Problems cannot be ignored. Serious health and safety issues are involved. Everyone who works in an aquatic facility needs to be made aware of the importance of a clean and healthy environment.

    Chlorinated pools can trigger asthma according to research from several sources. These findings may explain why swimmers are more prone to asthma than athletes in other sports.

    “Our results show, indeed, that nitrogen trichloride ,produced by chlorine, is a cause of occupational asthma in swimming pool workers like lifeguards and swim instructors,” says Dr. K. Thickett of the Occupational Lung Diseases Unit at the Birmingham Heartlands Hospital.

    As part of Dr. Thickett’s study, three employees of a local public swimming pool who complained of asthma-like symptoms were subjected to chloramine challenge tests. In a lab setting, they were exposed to roughly the same amounts of chloramine as they would be exposed at work (i.e., around the swimming pool, close to the surface of the water). Measurements of nitrogen trichloride were taken at 15 points around the pool, 1 m above the surface of the water. When exposed to equivalent amounts of the chemical in the lab, the three subjects all experienced significant reductions in forced expiratory volume in one second (FEV1), and high measurements on their Occupational Asthma Expert System (OASYS) scores, a measurement of asthma and allergy severity.

    Each of the subjects either stopped taking inhaled corticosteroids altogether or their asthma symptoms resolved significantly once they were placed in other occupations away from the swimming pools. Dr. Thickett’s study was backed up by research from other European and Australian sources.

    Investigators in Belgium have presented research showing that exposure to such chloramines greatly increases permeability of the lung epithelium, a condition associated with smoking cigarettes. In a study presented by Dr. Simone Carbonnelle, of the industrial toxicology and occupational medicine unit at the Catholic University of Louvain in Brussels, 226 otherwise healthy school children, mean age 10, were followed to determine how much time they spent around swimming pools and the condition of their lung epithelium. The children in Dr. Carbonnelle’s study were exposed to air around the school swimming pool for a mean of 1.8 hours per week. The level of lung permeability would be the equivalent of what she would expect to see in a heavy smoker, according to Dr. Carbonnelle. “These findings suggest that the increasing exposure to chlorine-based disinfectants used in swimming pools and their by-products might be an unsuspected risk factor in the rising incidence of childhood asthma and allergic diseases,” she said. The variation in lung surfactants persisted whether the children lived in a rural area or in the city and whether they were from upper income or less well-off families, she added.

    In the Belgium study, chloramines in the air around the surface of the pool were measured. In addition, three specific proteins were measured in the children: SF-A and SF-B (surfactant A and B) and Clara cell protein 16 (CC16). Surfactant A and B are lipid-protein structures which enhance the bio-physical activity of lungs lessening surface tension in the lung epithelium and preventing the collapse of the alveoli at the end of expiration. Anything that impairs the function of these surfactants will clearly impair lung function as well, because it makes the epithelium more permeable.

    Both of these studies were concerned with chlorine byproducts in the air above swimming pools. The problem isn’t the chlorine, but what chlorine turns into when combined with organics. The organics are contributed by bathers in the pool in the form of sweat, dander, urine and other organics. The chlorine reacts with the organics and produces nitrogen trichloride, aldehydes, halogenated hydrocarbons, chloroform, trihalomethanes and chloramines. If these sound like dangerous chemicals, they are.

    Other problems with chlorine
    Studies in the United States, Canada and Norway have linked chlorine byproducts in ordinary tap water to higher risks of miscarriages and stillbirths in pregnant women and increased incidences of bladder and colon cancer. Of disturbing news for swimming pool patrons are studies that show much higher levels of these chemicals are found in swimmers. The highest levels are found in the most active swimmers. The heightened risk is linked to exposure to a contaminant found in chlorinated water called trihalomethanes (THMs) which forms when chlorine reacts with organic material. THMs are a widely recognized carcinogen.

    While regulation changes in Canada and the United States have put tighter restrictions on the levels of THMs allowed in tap water, no such regulations exist for swimming pool water. This is in spite of a study that found a 1 hour swim resulted in a chloroform dose 141 times the dose from a 10 minute shower and 93 times greater than exposure by ingestion of tap water.

    Recent Studies on THMs in tap water include:

    • A study by California health department investigators Kirsten Waller and Shanna Swann examined the records of 5,144 pregnant women from the Fontana, Santa Clara and Walnut Creek areas. They reported a 15.7% higher chance of miscarriage among women who drank 5 or more glasses of chlorinated water per day.
    • A Canadian study reports that women who drink tap water containing high levels of trihalomethanes are twice as likely to have stillbirths. This Dalhousie University study reported that pregnant women increase their risk the more they drink or bathe in water containing the compounds. This study was reported in the scientific journal Epidemiology.
    • A Norwegian study of 141,000 births over a three-year period found a fourteen percent increased risk of birth defects in areas with chlorinated water.

    Despite these studies and the limited studies on swimming pool patrons, most swimming pool managers are probably unaware that they are exposing their patrons to THMs. This problem is not widely known and for the most part is ignored by the media. In swimming pools, the most obvious and instant signs of high exposure to these chemicals are red eyes, rashes and other skin irritations or problems. The highest exposure would appear to be for athletes and other swimmers who exert themselves physically in the water. Researchers report a mean chloroform uptake of 25.8 [micro]g/h for a swimmer at rest and 176.8 [micro]g/h) after 1 hour swimming. Other studies note that inhalation is an important route of exposure and is affected by various factors including the number of swimmers, turbulence and breathing rate. This means that for elite athletes, the risk of exposure at water level is significantly higher than for that of a casual swimmer. And in both cases, the dosages of THMs far exceed what is considered allowable by merely drinking a glass of chlorinated tap water.

    While the incidence of miscarriages and stillbirths is in itself cause for concern, other problems have been identified. Bladder cancer has been linked to chlorinated drinking water in an average of ten out of eleven studies. One of the studies in Ontario, conducted with funding from Health Canada, found that fourteen to sixteen percent of bladder cancers in Ontario showed a direct correlation to drinking water containing high levels of chlorine by-products. Chlorinated water has been linked to colon and rectal cancers in the studies, but the occurrences were not as common as those for bladder cancer.

    Possible Solutions
    Dr. John Marshall, of the Pure Water Association, an American consumer group campaigning for safer drinking water, states: “It shows we should be paying more attention to the chemicals we put in our drinking water and we should be looking for other alternatives to chlorination. A number of safe, non-toxic options exist, such as treating water with ozone gas or ultra violet light.”

    While governments focus on tap water and reducing the levels of dangerous chlorine byproducts, it turns out there are also options that are available for swimming pool managers.

    Is ozone viable for swimming pools? Recently a chemical-free public swimming pool was installed in Fairhope, Alabama. It uses Ozone technology and avoids the use of chlorine altogether. This is a first for public pools in North America. The United States Navy Dolphin program has switched to ozone technology over the last several years. A spokesman there stated that these systems have delivered the best water quality they have seen out of any systems they tried.

    Numerous other private, public, commercial, waterpark and hotel and motel pools have switched to ozone technologies as people become more concerned about chlorine and chlorinated byproducts. Other than the issue of carcinogens and other health problems, what are the relative benefits of ozone versus chlorine?

    One of the main problems with adopting ozone is that there is a higher initial capital cost to the swimming pool compared to chlorine. However, over the life of the pool ozone and ultraviolet technologies reduce the on-going operating and maintenance costs. These costs can be significant. Chlorine is famous for destroying pool infrastructures, rusting ventilation systems and destroying pool liners. Ozone poses no such problems.

    The ozone pool will be much cleaner, which means dirt, grease, oils, organics and other materials will wind up in the filter system much faster than with chlorinated systems. If the filter and strainer maintenance is not stepped up accordingly, the pool recirculating system will slow down and the pool will actually look dirtier than with chlorine. However, proper maintenance of the filter system will solve this problem.

    Part of the problem in adopting ozone is that engineers, architects, pool builders and designers are not familiar with the technology. Some applications of ozone, particularly systems installed ten to fifteen years ago were plagued with technical problems. Even though ozone systems have been in regular use in Europe and other areas of the world since the 1950’s, pools here have generally relied on chlorine. Since our engineering, architectural and other technical training have all been geared to chlorine, it takes re-education to now apply ozone. Many people in these industries are reluctant to shift gears.

    What is the difference in technologies? Chlorine is a complex man-made chemical that found original use in the infamous mustard gas of the First World War. Ozone has been in use for over 100 years, primarily in Europe and was first put to use for water purification, odor control and in hospitals. Ozone is made from oxygen or O2, which is converted through electricity to ozone or O3. Ozone is a much more powerful oxidant than chlorine. However, the shelf life of ozone is limited. It must be manufactured and used on-site. This is done through ozone generators which convert oxygen in the air into ozone.

    Ozone is considered a short-term disinfectant and chlorine is considered a long-term disinfectant. Chlorine is also an entrenched technology. It has been widely used in North America and was first adopted at the turn of the century. It is still the reigning champion of disinfection and has many supporters in the chemical and swimming pool industries.

    Some of the Issues
    There are credible researchers telling us that chlorine has some very serious health consequences when used as a sanitizer in swimming pools. The obvious question is why hasn’t the swimming pool industry adopted alternative technologies on a much more industry-wide basis? After all, ozone technology for swimming pools has been in regular use for over 50 years in Germany, France and other European nations.

    Let’s examine some of these issues. For drinking water or swimming pools, the European strategy is to use ozone to reduce the organic load in water. When chlorine is required for long-term disinfection such as distributing water through a municipal water distribution system, they use a very small amount of chlorine, thus reducing the risk for people drinking the water.

    It is the organics that cause problems when combined with chlorine. By reducing the organic load, the Europeans keep the chloramines at a very low level. In European swimming pool systems, the same thought process prevails. In Germany, for example, the strategy is to use a large surge pool that the public doesn’t even see to apply ozone or disinfection chemicals. The disinfection by products are then removed by various filtration processes prior to the water being returned to the pool with a slight dose of chlorine. Under these standards, swimming pool water is essentially treated to drinking water standards.

    The North American model developed under much different circumstances than the European. In North America, chemicals were adopted wholeheartedly around the turn of the century as the answer to the larger, more expensive European models of water treatment. Engineers here found they could build water treatment plants and swimming pools at greatly reduced capital costs if they used what were then considered miraculous chemicals to treat water. And, for the most part, the systems did what they were designed to do and that was to kill micro-organisms that could lead to sickness and death. What they didn’t anticipate was that chemicals like chlorine would have very serious side effects. In North America we are now stuck with swimming pools that in Europe would be considered surge tanks. The problem is to evolve ozone or other technology that can retrofit swimming pools in an economical manner. These systems are now starting to appear in the marketplace. It is not easy to engineers that switching to ozone technology is the way to go. Some of the earlier North American produced ozone systems were problematic and many engineers do not want to risk specifying equipment if they are not comfortable with the process.

    The technology is becoming very reliable. Without a doubt, ozone is starting to gain a foothold in water treatment and for swimming pools in North America. Some of the largest ozonation plants in the world have been built in the United States. Major North American cities such as Los Angeles, Dallas and Montreal, Canada have installed large ozone plants for water treatment. Some of the major pool operators in North America including Disney’s water parks use ozone technology. The United States Navy has switched to ozone systems for their Dolphin programs.

    Other encouraging signs include the City of Fairhope, AL which has distinguished itself with the implementation of an Olympic-sized swimming pool that is operated as ozone based with only slight chemical assistance. Many consumers are also requesting ozone systems for their backyard swimming pools. Regulations for these pools do not require them to use chlorine or other chemicals and many owners are now opting for ozone systems. Once pool owners switch, they realize that they no longer have to put up with red eye, rashes and the health consequences of chlorinated pools.

    As the technology becomes more prevalent, expect to see more expertise among local pool builders or pool maintenance companies. However, many of these companies rely on repeat sales of chemicals. These companies may be highly resistant to ozone systems as after-sales revenues will drop. However, for pool maintenance companies ozone is a good thing. They should spend less time maintaining pools and the pools will be cleaner and the water more appealing. In the future, expect ozone prices to drop. With better educated consumers, demand for systems will definitely increase.

    UV does not replace chlorine but allows you to run a lesser residual chlorine reading and allows the chlorine to be used totally for disinfecting rather than go into combination with other elements. State departments of public health have copies of state regulations and limitations for using UV in commercial pool applications. Codes vary.

    Ultraviolet or UV

    Ultraviolet light is part of the light spectrum, which is classified into three wavelength ranges:
    – UV-C, from 100 nanometers (nm) to 280 nm
    – UV-B, from 280 nm to 315 nm
    – UV-A, from 315 nm to 400 nm.

    UV-C light is germicidal, that is it deactivates the DNA of bacteria, viruses and other pathogens and thus destroys their ability to multiply and cause disease. It also breaks down chloramines that develop in indoor swimming pool water. Specifically, UV-C light causes damage to the nucleic acid of microorganisms by forming covalent bonds between certain adjacent bases in the DNA. The formation of such bonds prevents the DNA from being unzipped for replication, and the organism is unable to reproduce. In fact, when the organism tries to replicate, it dies.

    Ultraviolet technology is a non-chemical approach to assist disinfection. In this method of disinfection, nothing is added to the pool water except chlorine and pH control chemicals. This makes this process simple, inexpensive and requires very low maintenance.

    Ultraviolet purifiers utilize germicidal lamps that are designed and calculated to produce a certain dosage of ultraviolet (usually at least 16,000 microwatt seconds per square centimeter but many units actually have a much higher dosage.)


    • under sink installs & water vending machines
    • aircraft, boats & recreational vehicles
    • water wells & water cisterns
    • swimming pool & hot tubs
    • farms, ranches & trailer parksschools & hotels
    • aquarium, hatcheries and nurseries

    Short wave low pressure mercury vapor tubes produce ultraviolet wavelengths that are lethal to micro-organisms. Approximately 95% of the ultraviolet energy emitted is at the mercury resonance line of 254 nanometers. This wavelength is in the region of maximum germicidal effectiveness and is highly lethal to virus, bacteria and mold spores. Therefore, the water or air that passes through the chamber is exposed to the germicidal UV light and the genetic material of the micro-organism is deactivated, which prevents them from reproducing.

    UV or OZONE ?

    Currently UV gets our vote as easier to use and more effective.  Check with the USA Swimming Facilities Development Department for manufacturers to contact.

    Hello world!

    Welcome to This is your first post. Edit or delete it and start blogging!