In Denmark it has been discussed in the last about 5 years if reducing the pH in swimming pools below the traditional range of 7.2-8.0 can improve the chlorination by-products profile. Some studies including our own results suggests that THM and combined chlorine (chloramines) decreases if the pH is maintained below 7.0, but our own results show an increased formation of the geno-toxic haloacetonitriles (HANs) and we could also confirm old literature reports that trichloramine formation increases drastically at pH below 7.0.
We have learned that the recommendations and/or regulations for pH in chlorinated swimming pools vary considerable between countries. Can anybody tell that the regulations are in different countries and most interestingly if they know that the basis of the regulation is?
Article Effect of pH on the formation of disinfection byproducts in ...
Hi Henrik
The pH value and the concentration of the disinfectant in the water are important parameters. In Malaysia, the pH value should be maintained between 7.0 and 7.2 according to the regulations set by central government.
while I was reading a US guidelines for swimming pools, its stats that the chemical quality of the water shall be maintained in an alkaline condition at all times with the pH between 7.2 and 7.8.
Hi Muhammad,
It sounds like Malaysia already have made a very good choice for pH in swimming pools.
My group is just about to submit a follow up study of the effect of pH in swimming pools for disinfection byproducts formation to a scientific journal. We conclude that the optimal value for pH is as narrow as 7.0 to 7.2, exactly as you already have in your regulation.
That sounds good, shall be waiting for the article to come online, am interested to read your findings...:)
Actually in Malaysia, skin diseases are more common and what I think these may due to high humidity, even, we cannot wear clothes if hanged for a week inside, this cause skin infections, I am not sure about the municipal water supply pH regulations (need to check), so I think there may be some connection between the skin infection and pH, may be or may not be...:)
The paper will most likely take many months. I just remembered that we have a poster online with some of the data about finding the optimal pH for pool water for minimizing the disinfection by-products.
Poster Effect of pH on formation of chlorinated byproducts in swimming pools
In the Netherlands, the current regulations allow a pH window between 6.8 and 7.8. The Dutch regulation for swimming pools is now being renewed. For the new legislation, the pH window is suggested between 7.0 and 7.6. This new legislation is planned to come into effect in 2015.
Free available chlorine residual, total chlorine residual, pH, total alkalinity, and calcium hardness are perhaps the five most critical pool water care factors that, if not managed properly, can lead to pool water chemistry problems.
Considering pH experts generally agree on a pH that ranges from 7.4 to 7.6.
Hi!
the pH of most in swimming pools in Iran about 7.2 to 7.6 ... this standard sent from Iranian Environmental Health Organisation (every year). High pH can also create problems of its own. When pH values climb too high (7.8 and up), the pool water has a tendency to look dull or flat. High pH can also cause skin and eye irritation. When the pH rises, the sanitizer becomes less effective. This means the pool will require more sanitizer to keep it clean.The pH of pool water has a great effect on how comfortable it is for swimmers. Your eyes have a pH of about 7.3 to 7.5. As mentioned above, when pH strays too far away from this point, pool water becomes increasingly uncomfortable. Red, irritated eyes are an indication that the pH might be out of balance and should be checked.Taking all this into consideration, you will best meet your objective by keeping the pH between 7.2 and 7.6. This range combines the maximum swimmer comfort with sanitizer effectiveness.
It seems that most of you have quite reasonable pH values in your national regulations.
Our paper is finally published and it agrees with Maartens information on the Dutch new standard that pH should not be below 7.0.
Article Optimal pH in chlorinated swimming pools - Balancing formati...
I found a description of a suggestion to run pools at pH around 8.0. They promise a explanation in a paper that will come later. Does anybody know about this idea or have comments?
http://www.poolsolutions.com/gd/hiphpool.html
Another aspect of pool pH to consider is that low pH causes pool water to be "agressive" and dissolve metals and plaster surfaces, whereas high pH causes water to "scale" or deposit calcium carborate on pool surfaces making them feel rough to the touch and more likely abrade skin. So, maintaining a moderate pH avoids these extremes.
Dear all! My comment - or question ... if we leave aside the legal limits for the pH of swimming water, which pH is more comfortable for swimming? My personal experience is slightly alkaline is better than neutral which is again better than slightly acid.
The factors Rolf mention together with the formation of the very irritating and volatile, trichloramin, at pH lower than about 7 have been the reason for keeping pH around 7.4 up to 8.5 earlier.
I believe the reason it is discussed in technical circles to change pH in pools is the that the materials used in swimming pools have changed:
* Metal parts are often a higher grade of stainless steel that can tolerate low pH and high chloride concentrations.
* The pipes in the system are PVC or other polymer materials that don't corrode at all.
*The mortar in grit and glue for the tiles can be very pH resistant 2-component products.
* Some pools even use ion exchange to soften the fill water to prevent scaling in membrane or other very tight filters. Therefore we can technically choose to operate at high pH without scaling problems and low pH without corrosion.
I find water at about pH 6.5 more pleasing. It appears almost tasteless or slightly sweet to me.
As soon chloramines are present in the water the water is much better at pH around 7.5.
You should aim for a pH level of between 7 and 7.6. If the water pH is higher than 8, anyone who swims in the pool is at risk of skin rashes, while a pH of lower than 7 can sting the swimmers' eyes.Some of the many factors that can affect your pool's pH level include heavy rain, lots of swimmers and pool chemicals. Remember to regularly check your pool's pH level.http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Swimming_pools_water_quality
If anybody are still following this question they might find this modeling paper conclusion about the effect of pH in the pool interesting:
"Thus, the model indicates that the decrease of pH from 7.25 to 7 contributes to a significant increase of NCl3 formation i.e. about 40% with the same experimental conditions in the investigated pool."
Article Modeling of variations in nitrogen trichloride concentration...
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