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pH Control for Swimming Pools

Refreshingly simple pH control

Replacing hazardous chemicals with carbon dioxide (CO₂) for pH stabilisation in swimming pools delivers a range of benefits including an improved safety profile for staff and bathers, increased bather comfort, and a milder impact on the pool structure and the environment. In water, CO₂ forms a mild carbonic acid that also helps maintain alkalinity and reduce total dissolved solids. It forms a natural bicarbonate buffer which minimises peaks and troughs of pH.

The most widely used method is chlorination with sodium hypochlorite. However, it has its limitations. If the pH of the pool water is not kept between 7.2 and 7.6 the chlorinated water could cause eyes, skin and mucous membrane irritation to the pool users. At the same time, it would also become corrosive to pool's equipment.

Historically, pH control has been carried out with harsh solvents (mineral acids) that can be dangerous to handle. Carbon dioxide offers a clean and safe alternative for pH correction. When dissolved in water, CO₂ reacts to form carbonic acid, a weak acid capable of safely reducing the pH to the desired value. Recuperated from natural processes, it is also an environmentally friendly solution.

Download CO₂ – pH Control in Pools brochure

​Benefits of Using CO₂ as a pH-reducing Agent

Minimize potential hazards

The risk of chlorine gas fumes produced by an accidental reaction between a strong acid and hypochlorite is eliminated

Less Maintenance Costs

Lower maintenance costs as no corrosion is caused by strong acids

Precise pH Control

Over-acidification risk is eliminated as the reduction in pH is more gradual than with mineral acids, enabling more precise control of the pH

Reduced Chloramines Generation

There is a 30% reduction in oxidant levels, which is especially important at the water surface level

Refreshingly Simple pH Control

  • A superior safety and comfort profile for staff and bathers
  • Safe to use. CO2 is inert and requires no manual handling, reducing the potential of hazardous chemical interactions
  • Self-managing solution delivers a consistent level of pH, eliminating peaks and troughs
  • Lower environmental impact and a reduced level of total dissolved solids means less pool and plant corrosion

Interested in learning more about pH control in pools?

Our experts will work with you to design the best solution for your needs.


Our customer Everybody Sport & Leisure uses the Carbostore system for its safety profile

“Using CO2 for pH reduction brings safety benefits to the business as well as supports our key company values of sustainability and taking care of our staff.  The Carbostore system is self-managing, meaning that my staff do not need to handle hard acids and the risk of hazardous chemical interactions is minimised.  We have a remote fill point for our system, which means that we can get a delivery at any time of the day or night without having to manage a delivery check in,” reports Peter Wilson, Leisure Manager. 

The Equipment Needed to Supply and Dose the CO₂ Consists of:

  • CO₂ tanks (cylinders, dewars, etc.)
  • A CO₂ pressure and flow regulation system
  • Automated pH control
  • CO₂ diffusion system
  • Pipes from the CO₂ storage to the injection point
Learn More


Air Products gases, typically provided in gaseous and liquid form, enable customers in a wide range of industries to improve their environmental performance, product quality, and productivity.

Carbon Dioxide

Our experienced applications teams across the globe can use their industry and application knowledge to provide you with a compressed or liquid carbon dioxide supply and technology solution to meet your unique needs.