How To Lower pH in Pool? Why High pH Can Be Dangerous.

Maintaining proper pool water chemistry is important for the comfort of swimmers and also to protect the materials that the pool is made up of. 

The right balance of chemicals helps keep harmful bacteria and germs in check. Keeping pH levels under control is often challenging for pool owners as they are affected by everything that enters the water! In this post, we will learn...

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  • What is pH? 
  • What factors affect the pH levels of pool water? How pH level affects the pool environment and swimmers? 
  • How to keep pH levels within the ideal range? How to lower the pH of your pool if necessary? 

Most importantly, we will learn all this without making anybody’s head spin, while steering clear of in-depth chemistry and jargon.

After all, what matters most is that you, being a pool owner, must have functional knowledge of pool pH so that it’s safe for swimming in.

​This is much like driving a car. As a driver, you do not need to understand the theory behind the steering, engine, brakes, gears etc; you just need to know how all the controls function.

​Let’s begin.

​What Exactly Is pH?

​Simply put, pH stands for ‘Power of Hydrogen’. It is a measure of the concentration of hydrogen ions in a water-based solution.

​In layman’s terms, pH is a scale that determines how acidic or alkaline (basic) a solution is. The pH of a solution can measure anything between 1 to 14.

​Any solution with a pH of above 7 (up to 14) is alkaline and a solution with a pH less than 7 (up to 1) is acidic.

​Pure water has a pH of 7, which is considered neutral. Hence, pure water is neither basic nor acidic.

​A higher pH is an indicator of alkalinity and a lower value, of acidity.

​Interestingly, human tears have a pH between 6.5 to 7.6, with the mean value being 7.

​If pool water is too acidic, it can cause eye and skin irritation. Acidity also causes etching on the pool and leads to corrosion of pool equipment.

​On the other hand, if the alkalinity of pool water is on the higher side, it causes scaling and gives the water a murky, cloudy look. While this might not seem like too much of a problem, it is essential to note that a high pH can undermine the effects of chlorine. In such a case, the pool becomes unsuitable, even dangerous, for swimmers.

What factors affect the pH of pool water?

​Anything that is added to the pool alters the water’s chemistry and directly affects the pool’s pH. Cleaning agents, detergents, perfumes, swimmers’ waste, source water, rate of evaporation, dirt, debris etc cause a change in the pH. This is why it can be a bit tricky to find the right chemical balance in a swimming pool.

​The normal pH range of pool water is between 7.2 to 7.6.

​A pH of 7.4 is considered to be ideal.

​How do pH level affects the pool environment and swimmers?

​High pH leads to scaling and clogging of pipes and filters. This puts excessive strain on the pool equipment and affects circulation. It can even lead to a damaged swimming pool pump or motor or other problems that are expensive to fix.

​A pH of more than 8 can give the pool a cloudy look. Frankly, cloudy water is not exactly inviting. The whole point of having a pool is to have a place to relax and murkiness totally defeats this purpose and makes the pool repulsive.

​When pH levels rise above normal, the demand for chlorine goes up. It also leads to skin rashes and a burning sensation in the eyes.

​If the pH falls below normal, the pool water becomes acidic in nature and this too is a cause for concern. Low pH can cause metal corrosion, skin and eye irritation, staining, wrinkling of vinyl liners etc. Sodium carbonate and Sodium bicarbonate are the most commonly used chemicals to raise pH/alkalinity of pool water.

How to keep pH levels within the ideal range?

​It is important to test your pool’s chemistry on a regular basis.

​Of, the chemical balance is thrown out of whack because of inaccurate testing results. Hence, it is crucial that you use a high quality pool testing kit.

​Please note that improperly measured chemicals are often the culprit behind unstable/high pH levels. While adding chemicals, it is better to err on the side of adding less. You can always add more if necessary but once added, you cannot remove chemicals from the pool.

​Standard procedure dictates that you should shock (super-chlorinate) your pool every once in a while to make sure that the water is safe. However, shocking with calcium hypochlorite can cause pH levels to rise. Please test water meticulously before using the pool, especially after shocking.

How To Lower pH in Pool?

​Ok, now that we have understood what is pH and how it affects pool and swimmers, let us get down to the business of lowering it.

​Pool pH should be between 7.2 to 7.6. Alkalinity should be 80 to 120 ppm.

​If it is higher than that, you can lower it by adding acid. The most commonly used chemicals are Muriatic acid (HCl) or Sodium Bi-sulfate (Dry acid). Muriatic acid is also known as hydrochloric acid; it is an extremely strong acid and has a variety of commercial and industrial uses, such as melting rock! So use extreme caution while handling it and protect your skin and eyes.


Always check pool pH right before treating the water with acid. Refrain from adding chemicals to the pool in windy conditions as there could be blowback and/or spillage.

Here is a table that tells you how much Muriatic acid to add depending upon your starting pH level and pool size.

pH

1000 gal

5000 gal

10,000 gal

15,000 gal

20,000 gal

25,000 gal

50,000 gal

7.6-7.8

1 1/4 oz.

6 oz.

12 oz.

18 oz.

24 oz.

1 qt.

2 qts.

7.8-8.0

1 1/2 oz.

8 oz.

16 oz.

24 oz.

1 qt.

1 1/4 qts.

2 1/2 qts.

8.0-8.4

2 1/2 oz.

12 oz.

24 oz.

1 1/4 qts.

1 1/2 qts.

2 qts.

1 gal.

Over 8.4

3 oz.

16 oz.

1 qt.

1 1/2 qts.

2 qts.

2 1/2 qts.

1 1/4 gal.

 How do you to add muriatic acid to the pool safely?

  • Test pH
  • Determine the amount of chemical you need
  • Wear eye-googles and gloves
  • Measure out the acid
  • Turn off pump, add acid to the deep end of the pool and let sink to bottom. Now turn on pump so that it is circulated throughout the pool.
  • You can also pour it directly near the return jets
  • For above ground pools, add in small quantities at various spots and circulate manually.
  • Allow the acid to circulate
  • Re-test pH after 4 hours to determine whether pH is within the normal range.
  • Enjoy!

​A great way to ensure proper chemical balance in your pool is to clean it regularly.

Consider investing in an efficient robotic pool cleaner according to your needs and budget.

​We did the research for you, ​and recommend the #1 Top Rated Automatic Pool Cleaner ​- the Dolphin Nautilus CC Plus:

​BUT - If your pool tends to collect a lot of debris (leaves, ​bugs, etc) on top of the water, we'd suggest going with a pressure side cleaner such as the Polaris 360​.  

​The Polaris ​360 not only cleans the bottom of your pool, but it uses your pools return water to create a suction vortex which essentially pulls junk from your swimming pool into the bag attached to the top of the device.

​Unlike many pressure side cleaners, ​a booster pump is NOT required to use it, as it uses your swimming pools circulation pump!

Check ​out the Polaris 360 on Amazon, here.

Sharing is Caring! :-)
Jeff L.
 

Jeff has been an avid swimmer as long as he can remember, with his first swim lessons in Kindergarten in the 1980s, and became obsessed with pools and swimming shortly thereafter.

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