Have you ever wondered what pH stands for or where the term originated?

If your memory from chemistry class doesn't ring a bell, don’t worry. This brief history and guide tells you everything you need to know about pH.

Everything you need to know about pH

Have you ever wondered what pH stands for or where the term originated?

If your memory from chemistry class doesn't ring a bell, don’t worry. This brief history and guide tells you everything you need to know about pH.

A brief history of pH. The term “pH” was first described by a Danish biochemist named Søren Peter Lauritz Sørensen in 1909. pH is an abbreviation for “power of hydrogen” where “p” is short for the German word for power, potenz and H is the element symbol for hydrogen. The H is capitalized because it is standard to capitalize element symbols. The abbreviation also works with the French language — pouvoir hydrogen translates as “the power of hydrogen”.

What is pH? pH is really a logarithmic measure of the relative amount of hydrogen and hydroxyl in the water. Water that has more free hydrogen ions is acidic, whereas the water that has more hydroxyl ions is basic. pH is measured on a scale of 0–14. On the pH scale, zero indicates extreme acidity, 14 indicates extreme alkalinity and 7 indicates a neutral state. At 25° C the pH of pure water is very close to 7. Acids have a pH less than 7 while bases have a pH greater than 7. Pure water is considered neither an acid nor a base, but is the reference point for acids and bases. Each whole pH value below 7 is ten times more acidic than the higher value and each whole pH value above 7 is ten times less acidic than the one below it.

Why is pH important? pH is the single most important element in swimming pool water chemistry and pH affects every other chemical balance in pool water. When it comes to health, balance is everything. pH is the most important factor to maintain to keep pool and spa water balanced, healthy, and safe. Also, maintaining balanced pool water chemistry can save time and money on pool maintenance.

What is a healthy level of pH in pools and spas? What about drinking water? In pools and spas, a pH range of 7.4 to 7.6 is most desirable. Although the pH of pure water is 7, drinking water and natural water exhibits a pH range because it contains dissolved minerals and gases. Surface waters typically range from pH 6.5 to 8.5 while groundwater ranges from pH 6 to 8.5. Drinking water must have a pH value of 6.5–8.5 to fall within EPA standards.

How do you measure pH? pH can be measured with a drop-type test kit or a test strip test kit, which can be easily misread. Sutro is offering a solution to simplify monitoring and measuring accurate pH levels. Want to make pool care easier and have accurate pH measurements on your smartphone 24/7? Enter your email address here to get more information.

How often should you measure your pool’s pH? In-season, you should check your pool’s pH and chlorine levels at least twice weekly. The optimum time to test the pool water levels is at dusk at least four hours after all swimmers (including dogs) have left the water and at least eight hours after a rain or wind storm. If necessary, add products to re-balance your pool’s water quality.

What can you expect if the pH level in the pool is too low? Too high?

Simply put, water that is either too acidic or too alkaline will cause undesirable chemical reactions.

Low pH results in:

  • aggressive water, which can damage the mechanical components of the pool
  • irritation to the eyes and mucous membranes
  • pool liner damage
  • rapid loss of alkalinity

Solution? Alkalis are used to increase pH. Use sodium carbonate (soda ash) or sodium bicarbonate (baking soda) to raise pH.

High pH results in:

  • poorer chlorine disinfection
  • irritation to the skin
  • filter is overworked
  • cloudiness

Solution? Acids are used to lower the pH. Use muriatic acid (with caution) to lower pH.

To avoid the problems listed above, pH must be maintained between 7.2 and 7.8. For the best results, only use products recommended by your trusted professional pool and spa business. If you have specific questions about your pool or spa’s pH level, feel free to connect with us: hello@mysutro.com.

The way we value water is changing. Historically, water has been taken for granted and treated like an abundant renewable resource. The drought buzz recently is opening people’s eyes to the reality that water is limited and water quality is important. Understanding the importance of pH in your water is vital to health and vitality. Leaps in innovative technology give us the opportunity to solve the water problem and encourages everyone to participate. Join us in solving the water problem and find out how you can save water, money, and time on pool maintenance.


Carlos Smith - Apr 27, 2016


Congratulations for the beautiful design and concept for reading pH and Chloride in the swimming pool.Could you please tell us how accurate will be the pH and Chloride readings ? Is it necessary to perform time to time calibrations of the sensors ?

Thanks again for the great ideia.



Sutro - Apr 27, 2016

Hi Carlos!

Thanks for reaching out. Your feedback and support is important to us.

To answer your questions, calibration occurs every time a measurement is taken and the device readings will be accurate up to 1-2%.

Please send me an email to find out more about a special discount and feel free to send me any other questions you might have: marissa@mysutro.com

Thank you and looking forward to hearing from you!


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