When we talk about better commercial pool water treatment, it’s not always about adding more chemicals or more equipment. Sometimes, it’s about taking a closer look at how we manage the fundamentals.
pH control is one of those fundamentals.
Maintaining the correct pH plays an important role in effective sanitation, swimmer comfort, water balance and the overall performance of a commercial pool treatment system. While traditional acids have long been used to manage rising pH, carbon dioxide (CO₂) provides an alternative worth considering for the right aquatic facility.
At Brauer Swim, our approach has always been simple: water treatment should be fit-for-purpose. CO₂ isn’t the answer for every pool, but where conditions are suitable, it can provide some significant operational, safety and water-quality advantages.
Why Does Pool pH Need to Be Controlled?
Chlorine becomes less efficient as a disinfectant as pool water pH increases and overall water chemistry can become more difficult to manage.
An acid is used to bring pH back into the required operating range.
Traditionally, this has involved products such as hydrochloric acid or sodium bisulphate. CO₂ takes a different approach.
How Does CO₂ pH Control Work?
Rather than dosing a strong mineral acid into the circulation system, CO₂ gas is introduced into the pool water.
Once dissolved, the CO₂ reacts with water to form carbonic acid, which lowers pH. When integrated with an automatic water chemistry controller, CO₂ can be dosed according to demand to maintain a consistent pH setpoint.
This provides facilities with an automated method of pH control while reducing their reliance on traditional strong acids.
So, Why Consider CO₂?
1. Reduce the Handling of Strong Acids
One of the most practical benefits is reducing the amount of strong liquid acid being stored, transferred and handled within an aquatic facility.
Hydrochloric acid requires careful storage and dosing and can produce corrosive fumes. There is also a serious risk associated with accidental interaction between acid and hypochlorite products.
CO₂ removes this particular acid-handling process from day-to-day pool operation.
That doesn’t mean CO₂ is risk-free. It is a compressed gas and requires correctly designed storage, ventilation, gas detection and appropriate safety procedures. The system still needs to be engineered and installed correctly.
2. A Cleaner Approach to Water Chemistry
Mineral acids don’t simply disappear after doing their job.
For example, hydrochloric acid contributes chloride to the water, while sodium bisulphate contributes sulphate. Over time, these dissolved substances can accumulate and may need to be managed through water replacement.
CO₂ behaves differently. It adjusts pH through the pool’s carbonate chemistry rather than introducing the same residual chloride or sulphate load.
For facilities looking at the complete water chemistry picture, this is an important distinction.
3. Potential to Reduce Chlorine Demand
This is where CO₂ becomes particularly interesting.
Research published in Chemosphere investigated three indoor swimming pools operating with either hydrochloric acid or CO₂ for pH reduction.
During periods when CO₂ was used, researchers observed lower chlorine consumption while maintaining the required free chlorine levels.
This doesn’t mean CO₂ replaces chlorine, it absolutely does not.
What the research suggests is that the choice of pH-control method may influence more than pH alone and could potentially contribute to a more efficient overall treatment environment.
4. Potential Improvements in Indoor Pool Air and Water Quality
The same research also reported lower concentrations of certain oxidants in the air immediately above the pool water when CO₂ was used.
Researchers additionally observed reduced trihalomethane (THM) concentrations during CO₂ operating periods compared with periods using hydrochloric acid.
THMs are disinfection by-products that can form when chlorine reacts with organic material in the water.
Importantly, these findings should not be interpreted as meaning CO₂ alone solves indoor air-quality or disinfection by-product issues. Ventilation, bather load, sanitation, filtration, secondary treatment and overall water management all play a role.
However, the findings demonstrate why the method used to control pH deserves consideration as part of the complete water treatment system.
What About Corrosion in the Plant Room?
Anyone who has spent time around commercial aquatic plant rooms understands what a harsh chemical environment can do to equipment.
Acid fumes can contribute to corrosion of surrounding metalwork, electrical components, equipment and building infrastructure.
Reducing the storage and handling of fuming acids can therefore have benefits beyond simply controlling pool water pH.
For Brauer Swim, this is an important consideration because a plant room should never be viewed as a collection of individual pieces of equipment. Every component and chemical process can influence the performance and lifespan of the system around it.
Is CO₂ Suitable for Every Commercial Pool?
No, and this is important.
The effectiveness and practicality of CO₂ depends heavily on the individual pool and its source water.
Water with high total alkalinity can require significantly more CO₂ to achieve the required pH reduction. High calcium hardness can also create additional water-balance considerations.
Highly aerated environments can present another challenge. Water features, vigorous aeration and some spa applications can accelerate the release of dissolved CO₂ from the water, potentially making the process less effective or economical.
Before recommending CO₂, factors such as these should be assessed:
- Source water chemistry
- Total alkalinity
- Calcium hardness
- Pool volume and turnover
- Bather load
- Water features and aeration
- Existing sanitation and filtration systems
- Required dosing capacity
- Plant room configuration and ventilation
- CO₂ storage and delivery requirements
- Water chemistry monitoring and control
This is why correct system design matters.
What Does a CO₂ Installation Involve?
Depending on the size and requirements of the facility, CO₂ may be supplied through cylinders or a larger bulk storage arrangement.
The stored CO₂ passes through pressure-regulation equipment before being introduced into the pool circulation system at a specifically designed injection point.
Because CO₂ is heavier than air, storage areas require careful consideration. A leak in an enclosed or poorly ventilated area can allow gas to accumulate, creating a potentially dangerous environment.
Correct ventilation, appropriate gas detection, compliant storage and professional installation are therefore essential parts of the system, not optional extras.
The injection point also needs to be correctly engineered to promote effective dissolution while considering the other equipment within the treatment system.
What About Cost?
Looking only at the purchase price of CO₂ doesn’t necessarily provide a fair comparison with traditional acid dosing.
Facilities should consider the whole-of-life operating cost.
That can include chemical purchasing, storage infrastructure, personal protective equipment, staff handling time, maintenance, corrosion-related damage, dosing equipment and ongoing water management.
The lowest-cost chemical isn’t necessarily the lowest-cost solution once the entire plant room is considered.
pH Control Is Only One Part of the Bigger Picture
At Brauer Swim, we don’t believe any single technology should be looked at in isolation.
Good commercial pool water treatment comes from understanding how water chemistry control, primary sanitation, secondary sanitation, filtration, hydraulics and operational practices work together.
CO₂ can provide a valuable alternative to traditional acid dosing, particularly for facilities looking to reduce acid handling and take a more considered approach to their overall water chemistry.
But, like every piece of commercial water treatment technology, it needs to be correctly assessed, correctly sized and correctly integrated.
Is CO₂ pH Control Right for Your Facility?
Before changing how your facility manages pH, look beyond the chemical drum.
Consider your source water, existing treatment equipment, plant room environment, bather load and long-term operational requirements.
The goal isn’t simply to lower pH. It’s to create a safer, smarter and more effective water treatment system.
Talk to the Brauer Swim team about whether CO₂ pH control could form part of a fit-for-purpose solution for your aquatic facility.
Technical note: The research findings discussed in this article are based in part on the study “Benefits of carbon dioxide as pH reducer in chlorinated indoor swimming pools” by Gomà et al., published in Chemosphere (2010), together with industry guidance relating to the use of carbon dioxide for swimming pool pH control.
