One of the most common causes of pool water problems in heated swimming pools is the presence of chloramines. Chloramines, also referred to as “combined-chlorines” , are molecules formed by the combination of chlorine in the form of Hypochlorous Acid (HOCl) and organic wastes (saliva, perspiration, urine) in the form nitrogen or ammonia. Chloramines produce the “chlorine odour” that many people do not like (tear gas is a form of Chloramines).
When people complain of “too much” chlorine, it is almost always a case of combined chlorine or chloramines as opposed to a proper level of Free Available Chlorine (FAC) that creates the odour. The misconception is that the pool “smells of chlorine”, therefore (in the pool owners mind) they have too much chlorine present in the pool. At this point they usually stop adding anything to the pool, effectively ignoring the problem. Pool owners are seldom convinced that their true problem is a “lack” of chlorine and in particular FAC.
Chloramines are the root cause of many problems in pool water. Chloramines cause problems because of their stability and persistence. This stability and persistence forms additional Chloramines. This is chlorine demand (consumption) at its finest. (Consumers complain that they “just shocked” the pool but there’s no chlorine showing when tested.) As more chlorine is added without reaching breakpoint oxidation, more chloramines are formed thereby exacerbating the problem leading to “obvious problems” such as cloudy water or algae growth. Pool owners (and sometimes pool schools) unfamiliar with chloramines and chlorine demand, often try to treat the symptoms (cloudy water or algae) rather than dealing with the root cause. Without this awareness of chloramines & chlorine demand, pool owners may never receive the help they need.
Associated problems
Chloramines (combined chlorine) are poor sanitisers. The presence of chloramines (and dichloramines/ trichloramines) causes the following physical symptoms:
• red, burning eyes;
• burning sensation in nose, throat and lungs;
• dry, itchy skin and dry hair;
• Breathing difficulty, particularly in young children.
• A strong odour of chlorine around the pool
Furthermore, the pool has a tendency to become cloudy or green due to the low sanitising ability of the combined chlorine (chloramines).
Chlorine demand:
When chlorine is added to water, some of it is soon consumed by destroying algae, bacteria and other oxidisible material in the water. The amount of chlorine so consumed is referred to as the chlorine demand of the water. Only once the chlorine demand is satisfied, can any additional chlorine added be tested as a chlorine residual. Two types of chlorine residual can exist: 1. Free available chlorine residual - this is the chlorine available to do its job of sanitising the water. 2. Combined chlorine residual –this is chlorine combined with simple nitrogen compounds such as ammonia and urea. This chlorine (or more correctly chloramines) is not as nearly as effective as free available chlorine.
It’s essential to maintain a free available chlorine (FAC) residual at all times, to achieve sparkling clear, hygienic pool water. This is accomplished by regular shock treatment. Shock treatment (super chlorination) consists of simply adding a larger than normal dose of chlorine to burn out nitrogenous waste. When chloramines are removed by a shock treatment, better efficiency of chlorine is achieved. More of the chlorine residual can then exist as the free or active form, rather than as the less effective combined form.
Testing for chlorine in pool water
All good chlorine test kits and pool test strips allow you to determine free chlorine as well as total chlorine. Combined chlorine is calculated from these values as follows:
Combined chlorine = total chlorine - free chlorine
The combined chlorine value should ideally be as close to zero as possible. Some cheaper test kits use liquid reagents (drops. If the reagent bottle is marked "OTO" then you should consider a better test kit. OTO (orthotolodine) using a yellow colour chart, will show only Total Chlorine, not differentiating the difference between FAC and chloramines present. Chlorine testing using the more accurate DPD tests, using a pink colour chart, provides separate tests for Free Chlorine as well as Total Chlorine and is therefore preferable.
Destroying combined chlorine compounds
The appropriate amount of chlorine needed to reach breakpoint oxidation – usually recognized as 10 ppm FAC (free available chlorine) to correct each 1.0 ppm of combined chlorine. Failing to reach this level actually contributes to the chlorine demand problem as more chloramines are formed. Your pool professional may advise you to put in a larger than normal dose of shock treatment in your cloudy pool. When chloramines exist, this is necessary in order to reach breakpoint oxidation. Breakpoint oxidation is simply a level of 10 or more times of chlorine compared to that of the combined chlorine level. That means potentially adding large amounts of shock at one time! Yes, at one time!
Reaching breakpoint chlorination is an “all or nothing” action. Think of it as trying to jump across a divide; you can’t “come close”. You must reach the other side. You can’t “almost make it.” Whether you’re 5 centimetres short or 50 metres short, you still did not make it, and along with it comes the fall.
Conclusion
This is why we constantly remind consumers of the need to “shock” their pools. Weekly shocking during the summer months when the pool is in use will greatly reduce the potential of chlorine demand and may potentially even reduce consumption in the long run.
Showing posts with label chloramines. Show all posts
Showing posts with label chloramines. Show all posts
Thursday, 23 February 2012
Tuesday, 14 February 2012
Stabilised Chlorine - Friend or Foe?
Stabilised Chlorine - Friend or Foe?
Cyanuric acid (stabiliser) has been in use for almost 60 years and has been generally accepted as the most effective stabiliser of chlorine. The use of stabiliser is common in swimming pools around the world to reduce the loss of free chlorine by UV radiation. Up to 90% of chlorine residual may be lost within a few hours when exposed to sunlight. The addition of stabiliser may reduce this loss to only 10 to 15% of the total chlorine residual.
Many studies and investigations have been conducted to prove that stabiliser reduces the efficacy of chlorine. Studies have even been funded by manufacturers of competitive products.
In laboratory experiments, it was found that stabiliser resulted in the need for greater quantities of chlorine to achieve the same effect as lower chlorine concentrations without stabiliser (E. B. Robinton and E. W. Mood, American Public Health Association, 1965).However, other studies performed under swimming pool conditions, reported that stabiliser did not reduce the efficiency of chlorine, but in some instances actually improved the efficiency.
1. Sommerfeld and Adamson 1981. Cyanuric acid, used as chlorine stabiliser in swimming pool water, it seems has a relatively minor effect on the algicidal efficiency of free available chlorine. The toxicity of free available chlorine to 3 typical types of swimming pool algae was reduced slightly by 25 ppm of stabiliser, but then less than ideal levels of chlorine were employed in the test. Higher stabiliser concentrations (up to 200ppm) generally resulted in no further reduction in the algicidal efficiency of free available chlorine.
2. Robinton and Mood 1967 found no significant difference in the bactericidal activity of calcium hypochlorite and trichloroisocyanurates when the concentration of these compounds was expressed as free available chlorine
3. Kowalski and Hilton 1966. found that pools treated with stabilised chlorine have a better disinfection record than pools treated with chlorine gas or calcium hypochlorite.
4. Hodge 1959. found no toxicity to rats and dogs from sodium dichloroisocyanurate, one of the forms most commonly used to disinfect swimming pool water.
5. Clayton & Clayton 1981-1982. The immersion of the entire forearms of 10 individuals in a neutralized trichloroisocyanuric acid solution (100 ppm as available chlorine) 8 times daily for 7 days caused no irritation.
Results of research are often inconclusive or even contradictory thus cyanuric acid appears as both inhibitors and activators of chlorine. In practice and in the real world of outdoor swimming pool sanitising only benefits have been experienced with the use of stabiliser.
What is cyanuric acid? Cyanuric acid is marketed as a “Stabiliser” for swimming pools. What does stabiliser do? Stabiliser forms a weak bond with free chlorine in the pool water, protecting it from the sun’s ultraviolet rays to reduce chlorine loss. Properly managed, stabiliser has been shown to reduce the chlorine needed to maintain the ideal chlorine residual in an outdoor pool.
What are dichlor and trichlor? Dichlor and trichlor, also known as chlorinated isocyanurates, are two solid chlorine compounds that are widely used in outdoor and indoor swimming pools. Dichlor and trichlor contain both chlorine and stabiliser so it is not necessary to add stabiliser to the pool water. Dichlor usually comes in a granular form and is marketed for the residential swimming pool market. Trichlor is often sold in a tablet form for use in an erosion feeder.
I have an indoor pool. Should I use stabiliser? No there is no need. Remember that stabiliser is intended to reduce the loss of free chlorine caused by the sun’s ultraviolet rays. Indoor pools are not exposed to direct sunlight and therefore, there is no benefit in adding stabiliser to the pool water. How much stabiliser should be used in a swimming pool? Most pool chemical suppliers recommend that the optimal range for cyanuric acid is around 40 ppm. At levels above 50 ppm, pools reach the point of diminishing returns where the cost of buying stabiliser outweighs the benefit.
How much is too much stabiliser? Some international standards have set the maximum level at 100 ppm. However as previously stated no significant disadvantages are recorded even at much higher levels. How does one test for stabiliser? Any pool professional should be able to assist with these tests.
My pool has stabiliser levels above 100 ppm. Do I have to reduce them? The question is; are you experiencing problems with the pool and have you eliminated other factors such as a high TDS, combined chlorine, phosphates and chlorine demand problems. The traditional solution to supposed high stabiliser levels (“chlorine lock”) is to drain the pool. Clearly this solution will correct almost any problem that may exist. When this solution is suggested to you, make sure that it is your only course of action and that you are not unnecessarily wasting water. If you are not experiencing a problem, do not drain the pool – the naysayers will have it that the problem will occur but in the majority of cases this never happens, and when it does, it is usually related to other factors.
Recommendations 1 Stabiliser and stabilised chlorine (dichlor or trichlor) should be used in outdoor swimming pools to reduce the operating cost and maintain the hygiene effect by enhancing the longevity of chlorine in the presence of sunlight. 2. Both dichlor and trichlor also release stabiliser to the pool water. It is usually not necessary to add additional cyanuric acid into a pool that uses dichlor or trichlor. 3. Cyanuric acid should be tested at the beginning of each summer season and adjusted to at least 30 ppm for best effect during the season. 4. Pools that use stabiliser should, like all pools, maintain a free chlorine residual of 1- 3 ppm. 5. Most importantly, regularly have your pool water tested by a Pool Professional with a computerised water testing facility and ensure that your pool water remains chemically balanced for best results.
Cyanuric acid (stabiliser) has been in use for almost 60 years and has been generally accepted as the most effective stabiliser of chlorine. The use of stabiliser is common in swimming pools around the world to reduce the loss of free chlorine by UV radiation. Up to 90% of chlorine residual may be lost within a few hours when exposed to sunlight. The addition of stabiliser may reduce this loss to only 10 to 15% of the total chlorine residual.
Many studies and investigations have been conducted to prove that stabiliser reduces the efficacy of chlorine. Studies have even been funded by manufacturers of competitive products.
In laboratory experiments, it was found that stabiliser resulted in the need for greater quantities of chlorine to achieve the same effect as lower chlorine concentrations without stabiliser (E. B. Robinton and E. W. Mood, American Public Health Association, 1965).However, other studies performed under swimming pool conditions, reported that stabiliser did not reduce the efficiency of chlorine, but in some instances actually improved the efficiency.
1. Sommerfeld and Adamson 1981. Cyanuric acid, used as chlorine stabiliser in swimming pool water, it seems has a relatively minor effect on the algicidal efficiency of free available chlorine. The toxicity of free available chlorine to 3 typical types of swimming pool algae was reduced slightly by 25 ppm of stabiliser, but then less than ideal levels of chlorine were employed in the test. Higher stabiliser concentrations (up to 200ppm) generally resulted in no further reduction in the algicidal efficiency of free available chlorine.
2. Robinton and Mood 1967 found no significant difference in the bactericidal activity of calcium hypochlorite and trichloroisocyanurates when the concentration of these compounds was expressed as free available chlorine
3. Kowalski and Hilton 1966. found that pools treated with stabilised chlorine have a better disinfection record than pools treated with chlorine gas or calcium hypochlorite.
4. Hodge 1959. found no toxicity to rats and dogs from sodium dichloroisocyanurate, one of the forms most commonly used to disinfect swimming pool water.
5. Clayton & Clayton 1981-1982. The immersion of the entire forearms of 10 individuals in a neutralized trichloroisocyanuric acid solution (100 ppm as available chlorine) 8 times daily for 7 days caused no irritation.
Results of research are often inconclusive or even contradictory thus cyanuric acid appears as both inhibitors and activators of chlorine. In practice and in the real world of outdoor swimming pool sanitising only benefits have been experienced with the use of stabiliser.
What is cyanuric acid? Cyanuric acid is marketed as a “Stabiliser” for swimming pools. What does stabiliser do? Stabiliser forms a weak bond with free chlorine in the pool water, protecting it from the sun’s ultraviolet rays to reduce chlorine loss. Properly managed, stabiliser has been shown to reduce the chlorine needed to maintain the ideal chlorine residual in an outdoor pool.
What are dichlor and trichlor? Dichlor and trichlor, also known as chlorinated isocyanurates, are two solid chlorine compounds that are widely used in outdoor and indoor swimming pools. Dichlor and trichlor contain both chlorine and stabiliser so it is not necessary to add stabiliser to the pool water. Dichlor usually comes in a granular form and is marketed for the residential swimming pool market. Trichlor is often sold in a tablet form for use in an erosion feeder.
I have an indoor pool. Should I use stabiliser? No there is no need. Remember that stabiliser is intended to reduce the loss of free chlorine caused by the sun’s ultraviolet rays. Indoor pools are not exposed to direct sunlight and therefore, there is no benefit in adding stabiliser to the pool water. How much stabiliser should be used in a swimming pool? Most pool chemical suppliers recommend that the optimal range for cyanuric acid is around 40 ppm. At levels above 50 ppm, pools reach the point of diminishing returns where the cost of buying stabiliser outweighs the benefit.
How much is too much stabiliser? Some international standards have set the maximum level at 100 ppm. However as previously stated no significant disadvantages are recorded even at much higher levels. How does one test for stabiliser? Any pool professional should be able to assist with these tests.
My pool has stabiliser levels above 100 ppm. Do I have to reduce them? The question is; are you experiencing problems with the pool and have you eliminated other factors such as a high TDS, combined chlorine, phosphates and chlorine demand problems. The traditional solution to supposed high stabiliser levels (“chlorine lock”) is to drain the pool. Clearly this solution will correct almost any problem that may exist. When this solution is suggested to you, make sure that it is your only course of action and that you are not unnecessarily wasting water. If you are not experiencing a problem, do not drain the pool – the naysayers will have it that the problem will occur but in the majority of cases this never happens, and when it does, it is usually related to other factors.
Recommendations 1 Stabiliser and stabilised chlorine (dichlor or trichlor) should be used in outdoor swimming pools to reduce the operating cost and maintain the hygiene effect by enhancing the longevity of chlorine in the presence of sunlight. 2. Both dichlor and trichlor also release stabiliser to the pool water. It is usually not necessary to add additional cyanuric acid into a pool that uses dichlor or trichlor. 3. Cyanuric acid should be tested at the beginning of each summer season and adjusted to at least 30 ppm for best effect during the season. 4. Pools that use stabiliser should, like all pools, maintain a free chlorine residual of 1- 3 ppm. 5. Most importantly, regularly have your pool water tested by a Pool Professional with a computerised water testing facility and ensure that your pool water remains chemically balanced for best results.
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