Stink or Swim

by Pool Builders on 05-13-2014 in Articles

Swimmers will often blame the strong chemical smell of indoor pools on "too much chlorine". Skin that itches, red eyes, coughing, sore throats, asthma attacks, and other irritations and respiratory ailments- along with the strong odorare not due to chlorine; but to chloramines. These are chemical compounds that build up in swimming pools when it is not properly balanced. A chlorine odor in your indoor pool indicates a very high chloramine level, that your pool is out of balance, and lastly- you now have a highly corrosive environment!

Where do chlormines come from?

Chloramines form when "free" chlorine is combined with ammonia, nitrogen, and various other compounds that can be found in perspiration, feces, baby diapers, urine, body oils, lotions, perfumes, hair spray, and saliva to name a few. Swimmers can help to prevent this problem by showering before entering the swimming pool. We recommend signs be posted in all commercial natatoriums that showers must be taken before entering the pool. This alone will cut down more than 75% of the problem of patrons bringing "waste" factors in the pool.

A very high chloramine level indicates the pool chemistry is out of balance and in turn, creates a highly corrosive environment. Left uncontrolled, this chemistry attacks and destroys equipment, metal, wiring, controls, other surfaces, any other pool equipment, ladders, railings, controls, and structural members. There will be signs of rust, corrosion, "green" or "white" substances on equipment, mold within the structure in some areas... and this begins to deteriorate the pool dehumidifier. First compressors fail, contactors fail, coils begin to leak, etc.

A pool dehumidification system can remove excess moisture from the natatorium; however it cannot eliminate nor will any pool dehumidification system, (contrary to claims of special filters!) control the harmful chlorine compounds, control patrons entering the pool without taking showers, or children in diapers using the pool as their bathroom! Many companies today are recommending more outside air-meaning "dilution is the solution". Unfortunately, this has nothing to do with air flow and everything to do with the water quality, which HVAC contractors have no control over.

The pool dehumidifier does not cause this problem, nor can it "fix" the indoor air quality -as this is a water quality issue.

· Although some companies recommend blowing air across an open pool, we-along with many designers, do not recommend this procedure. Indoor pools are not (and should not be) designed to have large amounts of air blowing across a water surface. This air movement across the water cannot control chloramines, has a "chill effect" on patrons, and is a waste of energy because it increases evaporation rate of water. Chloramines are a "heavy sticky substance" and tend to lay at the pool surface area---where it is ingested by patrons. This accounts for the increase in asthma attacks and other respiratory type diseases now found in children that swim on a regular basis in commercial pools. It's dangerous to any human being especially the children and the elderly who may not have a great or fully developed lungs & immune system.

· Return air grilles should not be installed at the deck level or above the spa- to pull this contaminated air into the pool dehumidification system where it is highly corrosive. The return air in a pool room is generally installed at the highest (or near the highest, depending upon ductwork installation) point of the room. Warm moist air in a pool room rises and stratifies along the ceiling first. Dehumidification starts on the return air side by pulling this air through the system. Therefore, if the return air is at the deck level, the dehumidification system may not operate properly to control the environment and early deterioration of the structure & equipment may occur. Installing huge return air equipment at deck level may also interfere with negative pressure.

· Introducing a higher volume of outside air to an indoor pool does not control the water chemistry problem and also creates additional energy costs for owner/operators. Proper air turnovers and the air delivery system can help... but it still remains a water quality issue.

Automated Pool Chemistry feeders: these can become very problematic for commercial pools. Many do not realize that the sensors of these systems collect debris and become "gunked up" (excuse the term but it best describes this!) by the normal daily use of the pool. When they do, the they may send a message to the automated system is that there is not enough chlorine in the pool - and the chemistry feeder begins to dump even more chlorine into the pool; hence another reason why your pool room may "stink". The best approach to understanding pool chemistry is to contact your pool company and have your staff trained properly in how to balance a pool.

Salt water pools: If you are using salt, you have a much higher risk of deterioration and corrosion due to the highly corrosive nature of salt. This must be balanced properly. If your system has an external plate heat exchanger for pool heat recovery and it is stainless steel, most likely a Titanium Heat Exchanger will need to be purchased as these are typically destroyed by salt water in less than 18 months. We do not recommend salt water pools - they are difficult to balance, companies are all over the board with the PPM to be maintained - we've been told anywhere from 1800 PPM to 6400 PPM, and it appears no one company has been able to resolve the issues with corrosion due to salt.

Pool Balancing is not a daily function, it could be hourly depending upon how busy, how many people, and how many hours the pool is open.

Please note that certain rules are applicable to maintaining your pool water. Babies and small children should not be allowed in the pool with diapers or "leak proof" swim diapers. It's been proven - they leak and this bacterium enters the pool (generally Ecoli bacteria as babies and small children generally have a diarrhea as their stomachs are not as fully developed as adults.) It is recommended that in all commercial pools signs be posted that no children with diapers are allowed in the pool... period.

Chlorine, Salt, Bromine

You should not be able to smell chlorine when you walk into your pool room. It means the pool is not balanced properly. It is the responsibility of each end user/owner/client to be trained in proper pool chemistry and staff that maintain your indoor pool in the balancing procedures.

When pool water chemistry (salt, chlorine, bromine, etc.), is properly balanced- it will remain free of odor and protect bathers from bacteria and germs. Chlorine, the primary pool treatment process, kills germs and destroys harmful organic contaminants introduced into the water by bathers. Chloramines are formed in pools when chlorine molecules attach to ammonia and other organic by-products of the human body. Pool operators have traditionally controlled waterborne bacteria chemically with chlorine, meaning that the gaseous chlorine-based by-product can linger and re-circulate through the pool dehumidification system causing damage to components, wiring, contactors, relays compressors, etc. Although conventional mechanical fabric media filters on the dehumidification systems can trap airborne particulates, gases such as chloramines are not captured.

  • Improperly balanced pool water chemistry can attack the indoor pool's mechanical system, the building's structural components and anything metal in a pool room. When the water is not properly balanced this becomes a highly corrosive and unhealthy environment. Corrosion is the first sign of poor pool chemistry.
  • Combined chlorine compounds cause eye irritation and the so-called "chlorine odor" that swimmers often complain about. Free chlorine in water, under normal concentration, has no discernible odor. A pool dehumidification system will remove the excess moisture from the pool enclosure but will not eliminate the harmful chlorine compounds that cause the chlorine odor and metal corrosion. Many companies recommend blowing air across the open body of water and installing the system's return air at the deck level to assist in removal of chloramines. (A) Moving air across an open body of water increases evaporation rate and causes chill effects on bathers. This is not recommended for obvious reasons. (B) Installing returns at the deck level to pull the contaminated air off the pool surface now pulls highly corrosive chloramines into the mechanical system. Again, not recommended for the system's main return to be installed at deck level for that reason and due to stratification of moisture in pool rooms at the ceiling level. Warm moist air rises towards the ceiling areas first and foremost - the return air grille is installed at high point within the enclosure to pull this air off the ceiling areas into the dehumidification cycle. Only a comprehensive pool water chemistry program and continuous monitoring will keep your pool crystal clear and odor free.
  • Chloramines condense along with moisture from the pool on cold surfaces forming a corrosive chloride-rich solution.
  • The chloride solution forms a harmful substance that will corrode metals, including stainless steel, where it forms a particularly serious stress corrosion-cracking problem.
  • The chloramines in the air can cause significant damage to metal surfaces, such as windows, doors and frames, ladders, ductwork, pool heaters, & HVAC equipment.
  • The higher the concentration of chloramines in the air, the more corrosive the condensate.

Chlorine's efficiency at reducing ammonia is affected by several factors, including water temperature, water pH, total chlorine concentration, and level of dissolved solids in the water. Because of their higher operating temperature and higher ratio of occupancy per unit water volume, spas produce greater quantities of air contaminants than pools.

The following measures have demonstrated a potential to reduce chloramine concentrations in the air and water:

  • Ozonation. In low concentrations, ozone has substantially reduced the concentration of combined chlorine in the water. In high concentrations, ozone can replace chlorine as the primary disinfection process; however, ozone is unable to maintain sufficient residual levels in the water to maintain a latent biocidal effect. This necessitates maintenance of chlorine as a residual process at concentrations of 0.5 to 1.5 ppm.
  • Water Exchange Rates. High concentrations of dissolved solids in water have been shown to directly contribute to high combined chlorine (chloramine) levels. Adequate water exchange rates are necessary to prevent the buildup of biological wastes and their oxidized components in pool and spa water. Conductivity measurement is an effective method to control the exchange rate of water in pools and spas to effectively maintain water quality and minimize water use. In high-occupancy pools.
  • Air Turnovers, outside air, and properly designed duct work/air delivery systems can help but they cannot remove contaminants. Chloramines are almost like a "sticky substance" -- they have to be washed off when continual off-gassing of pools occur. Mechanical contractors have been blamed for the chlorine odors and the inability to remove these by moving more air flow in the structure or establishing return air at deck levels. Again, proper pool chemistry and pool balancing, working in conjunction with good air turnover rate is imperative.
  • It is highly recommended, that once the pool is established, all staff should be trained by the pool company in managing these areas.
  • Do NOT store chemicals in the mechanical space. People tend to forget to cap off chemicals tightly and they can escape into the mechanical space. Accidental spills also create a corrosive environment. It is recommended to store all chemicals separately from any mechanical equipment room.
  • Do NOT leave the mechanical room open to the pool room. A door should be installed between mechanical space and pool room environment to prevent chlorinated air travelling into areas such as mechanical spaces or other spaces of offices, buildings, and homes. Suspending equipment above an open pool spells long term disaster!

1. Chemical levels in the pool water must be maintained within acceptable limits at all times to avoid health hazards and/or possible equipment damage. Chlorine levels in excess of 6 PPM (parts per million) are to be avoided. pH levels below 7.2 and above 7.6 are to be avoided. If bromine is used - contact your pool company pool chemistry individual and determine where bromine should be kept at all times. Failure to follow these "rules' will result in pool equipment with deterioration, repairs, shortened life spans.

2. The stainless steel plate heat exchangers should not be used on salt-water pools with a level of salt in excess of 3200 PPM. Doing so will void the warranty and the manufacturer will take no responsibility for pool, dehumidification system and /or heat exchanger damage. If an external heat exchanger is used - a Titanium Heat Exchanger will always be recommended. Salt water pools are not recommended for indoor pools where pool dehumidification systems and duct work come into contact with poorly maintained chemistry.

3. Automatic chemical feeders should never be installed up stream of the system's heat exchangers. Super chlorinated water, such as produced by such feeders, can destroy the heat transfer surface within the exchanger. When automatic chemical feeders are installed downstream of the heat exchanger, certain precautions must be taken to prevent heat exchanger damage. A check valve (non-metallic) must be installed in the water piping between the heat exchanger and the chemical feeder. This will prevent the super chlorinated water in the chemical feeder from draining back into the heat exchanger when the pool water pump is shut off.

If a salt water pool, a titanium heat exchanger may be a more suitable option and additional protection against corrosion.

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