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Tech Note: pH Effects

Posted on 02/26/2019 | Maintenance - News - Uncategorized

According to industry standards, pH values in pools should remain between 7.2 and 7.8. I always tell customers that pH is the most important factor in your water chemistry, but I do not always tell them why. There are several reasons for this, which I will explain in more details here. So smack-dab in the middle of the 7.2 and 7.8 is the number 7.5. At a pH of 7.5 exactly 50% of your chlorine is working effectively. So for every two parts of chlorine that are in your pool, only one part is working. Yet if we get our pH only 1 point lower, to a 6.5, now over 90% of the chlorine is working and at a pH of 8.5, less than 10% of your chlorine is working. So let’s go through the scenarios that we hear every year:

Customer Jane Doe – “My pool is cloudy and my chemicals are perfect” is the phone call response we get when we answer the phone. So we ask how the chemicals are, “well the chlorine is 3.0, so the chlorine is even on the high side.” What Mrs. Doe does not tell us is that her pH is at 9.0, so really it doesn’t matter how much chemical she is adding, what she is adding is much less than 10% effective. In fact, as she keeps shocking her pool, she makes the issue worse because every time she adds shock, the pH continues to go up. Mrs. Doe needs to lower her pH before her chlorine will even work and she is causing scale formation in her equipment and on her pool shell because of her high pH.

Customer John Doe – “My chemicals are perfect but water is shooting out of my heater” is the phone call this time. We ask what the chemical readings are and Mr. Doe states that he’s not sure what the readings are but that the water looks perfect so the chemicals must be perfect. Unfortunately, when we go out to the pool, we find that the chlorine is almost perfect, maybe a little low… 0.6ppm, but that the pH is 6.0 so the water is very, very acidic. Good news is that the low level of chlorine that Mr. Doe has in his pool is more than enough to keep his pool looking great. Bad news is that the acidic water has attacked the one area most susceptible to chemical attack. The copper heat exchanger on his heater. Mr. Doe is now upset that he needs to spend $4,000 on a new heater, and we even suggest one to him that has a cupronickel heat exchanger that is more susceptible to pH changes. Unfortunately, Mr. Doe is not happy that he needs a new heater.

Good news is that there are many advances in water chemistry. Chemical automation, UV sanitation, salt chlorine generators. Now everything in life has a pro and a con to it as do each of these devices, but in some instances, the only con is the cost. Many of today’s new innovations for pools are brought to us with ease of use in mind, knowing that our customers don’t always like to spend as much time checking chemicals and want to spend more time enjoying themselves. For these same reasons, we also offer cleaning and chemical check packages for our customers as well. Most importantly, out of this message is that we want you to check more than your chlorine. Please know that checking your pH is actually even more important and that bringing a water sample to your pool professional or having them take it right in your back yard at least once a month can help prevent serious issues, even much worse than Mr. and Mrs. Doe have.

Happy Swimming!

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