Don’t Lower Pool pH with Acid

pool acid lowering

Pool water chemistry can be a mystery to many pool owners. A common assumption is that acid is the go to solution for balancing pH levels. While it is true that acid can lower pH, the story does not end there.

The indiscriminate use of acidic compounds, particularly hydrochloric acid or muriatic acid, can damage pool equipment, cause skin irritation, and result in long-term chemical imbalances.

This article will explore why you should not rely solely on acid to control pH in your swimming pool. It will also introduce safer and more sustainable alternatives that support swimmer safety, pool longevity, and overall water chemistry.

Understanding Pool pH Management

pH levels for swimming pool

What Is pH and Why It Matters

pH measures how acidic or alkaline your pool water is. The scale ranges from 0 to 14, with 7 being neutral. Anything below 7 is acidic, and anything above is alkaline. The ideal range for swimming pool water is between 7.2 and 7.8.

Maintaining pH in this range is essential for swimmer comfort and the effectiveness of pool chemicals like chlorine. A balanced pH prevents itchy skin, cloudy water, and excessive wear on pool surfaces and equipment.

What Happens When pH Is Too Low

When pH drops below 7.2, the water becomes acidic. Acidic water can:

• Cause skin and eye irritation
• Accelerate corrosion of pool equipment
• Erode grout, tiling, and pool surfaces
• Lower total alkalinity
• Increase metal staining

In other words, acidic water undermines the safety and usability of the pool.

What Happens When pH Is Too High

On the other hand, high pH levels (above 7.8) can:

• Lead to cloudy pool water
• Reduce chlorine’s ability to sanitise
• Create calcium scale build-up
• Result in itchy skin and irritated eyes
• Decrease water clarity and increase filter strain
• Damage swimwear and goggles over time

If your pool’s pH levels are consistently too high, you will experience both user discomfort and more maintenance demands.

What Affects pH Levels

The pH level in a pool does not stay constant. It is affected by many factors:

• Weather: Rain and heat influence chemical balance
• Swimmer activity: Sweat, lotions, and bodily fluids
• Water temperature: Warmer water typically increases pH
• Water features: Aeration raises pH over time
• Chemical additions: Chlorine, algaecides, and shock treatments

Testing the pH of pool water should be done regularly as pH levels can fluctuate due to these factors. The number of swimmers in the pool also significantly impacts pH levels, as their activity introduces various substances into the water.

All these elements influence whether your water is acidic or alkaline.

The Role of Total Alkalinity

Total alkalinity acts as a stabilising agent for pH. It keeps pH from swinging too quickly. The ideal range is 100 to 150 parts per million (ppm). If alkalinity is too low, pH may plummet, making the pool water too acidic. If it is too high, pH becomes difficult to adjust.

Many pool owners make the mistake of treating the pH without first adjusting total alkalinity. This leads to frequent chemical use and short-lived results.

Why You Should Not Lower pH with Acid

Why You Should Not Lower pH with Acid

Does Acid Lower pH in Pool Water?

Yes, muriatic acid and hydrochloric acid lower pH. However, the question should not be does acid lower pH in pool water, but should acid be your first choice? Acidic compounds, including dry acid (sodium bisulphate), are highly effective, but they come with side effects.

The Dangers of Muriatic Acid

Muriatic acid is highly corrosive. It produces toxic fumes, requires protective clothing, and can cause skin irritation on contact. Improper handling may result in chemical burns or respiratory issues. Even with precise dosing, overuse can disrupt other levels such as calcium hardness and total alkalinity. Additionally, it can cause significant skin and eye irritation, making it a hazardous choice for pool maintenance.

Too much acid in pool water can create:

• Metal corrosion
• Concrete etching
• Liner degradation
• Equipment breakdown
• Acidic water that irritates skin and eyes

Using acid without calculating pool volume and current chemical levels is like doing surgery without diagnostics. Pool volume must be calculated to determine the correct amount of acid needed to lower pH effectively and safely.

Chemical Alternatives for Lowering pH

Why Carbon Dioxide Is a Smarter Choice

Carbon dioxide (CO₂) is emerging as a safer, more sustainable way to lower pH in pools. Unlike hydrochloric acid, CO₂ does not pose immediate safety risks to swimmers or technicians. Additionally, using CO₂ to lower pH reduces the greenhouse gas emissions of pools, making it an environmentally friendly option.

Benefits of Using CO₂:

• Accurate pH control without damaging total alkalinity
• No dangerous fumes or corrosive effects
• No reaction with chlorine or other pool chemicals
• Reduces chemical handling risks
• Minimises greenhouse gas emissions when properly managed
• Stable results with fewer reapplications

CO₂ systems are installed to inject controlled amounts into pool water, lowering the pH naturally without acid shocks.

Dry Acid (Sodium Bisulphate)

Sodium bisulphate is another alternative to muriatic acid. While it is still acidic, it is safer and easier to store than muriatic acid. It is also typically preferred for its safety and convenience, especially for residential pool maintenance.

• Easier to store
• Less hazardous to handle
• More stable in dry form

However, like all acidic compounds, it can still harm pool surfaces and disrupt balance if overused. Both muriatic acid and sodium bisulfate can damage pool surfaces and skin if not handled properly.

Testing and Adjusting Pool pH

testing pool water

How to Test Pool pH Accurately

The most accurate method is using a digital pH sensor or electronic meter. These devices provide reliable readings and often measure other factors like total alkalinity.

For basic home testing, pH test strips are widely available and can still give a good indication of whether the pH is within range. These strips are a convenient and cost-effective way to monitor pool water quality, making them a practical choice for many pool owners.

Frequency of Testing

You should test your pool’s pH:

• At least 2 to 3 times per week during summer months
• After storms or heavy rainfall
• After high swimmer activity
• After adding chemicals

Since pH is sensitive to many factors, frequent testing is essential to avoid overcorrecting.

Target Ranges and Response Actions

• 7.2 to 7.8: Ideal range
• Below 7.2: Water is acidic. Add alkalinity increaser (baking soda or soda ash) before adjusting pH
• Above 7.8: Water is alkaline. Use sodium bisulphate or consider CO₂ injection
• 7.0 or below: Immediate action needed
• Above 8.0: Chlorine becomes far less effective

Always adjust total alkalinity first, then re-check pH before dosing.

Safety When Handling Chemicals

If you are using acid or sodium bisulphate:

• Wear protective clothing to prevent exposure to harmful chemicals
• Avoid inhaling fumes
• Never mix with other pool chemicals
• Add chemical to water, never water to chemical
• Calculate pool volume first to determine the correct amount
• Always wear protective equipment when handling chemicals that alter pool pH to ensure safety.

After adding chemicals, wait 15 to 20 minutes, then retest to verify pH changes before swimming resumes. This ensures that the adjustments have taken effect and the water is safe for use. Retesting after this period is crucial to confirm that the desired pH level has been achieved.

Effects of High pH in Pools

Swimmer Health and Comfort

High pH contributes to:

• Itchy skin
• Eye irritation
• Uncomfortable swimming experience
• Erosion of swimwear and goggles, which occurs faster than normal in high pH conditions.

If your pool’s pH is consistently high, swimmers will feel the effects and your water will become less inviting.

Chlorine Effectiveness

As pH rises, chlorine becomes less effective. You may be adding the correct amount of chlorine, but it will not sanitise properly in high pH conditions. This can lead to:

• Increased algae growth
• Cloudy water
• Increased need for other chemicals

Calcium Scale and Water Clarity

High pH accelerates the formation of calcium hydroxide, which causes calcium scale build-up in pools. This leads to:

• Scale on tiles, plumbing, and equipment
• Clogged filters and pipes
• Cloudy water and reduced circulation

Preventing these issues saves both time and money in pool maintenance and pool repairs.

Conclusion: Smarter pH Management for Australian Pools

Managing your pool’s pH is not just about dumping acid and hoping for balance. It requires an understanding of total alkalinity, water chemistry, and chemical interactions.

While acid can lower pH quickly, the long-term consequences are not worth the risk. Safer options like carbon dioxide systems, sodium bisulfate, and proper alkalinity adjustment are far more sustainable and safer for your pool and your family.

If you are unsure how to restore balance to your pool water, do not risk damaging your equipment or compromising swimmer safety.

Contact 1 Pool Care for professional guidance and ongoing support to keep your pool in pristine condition all year round.