What Is Soda Ash Used For in a Swimming Pool?
Soda ash, also known as sodium carbonate, is primarily used in swimming pools to increase the pH level and therefore also the alkalinity of the water. Its main function is to prevent acidic water from damaging pool surfaces and equipment, ensuring a safe and comfortable swimming environment.
Understanding pH and Alkalinity in Pool Water
Maintaining proper water chemistry is crucial for a healthy and enjoyable swimming pool experience. Two key parameters are pH and alkalinity.
pH (Potential of Hydrogen): This measures the acidity or basicity of the water. It’s measured on a scale of 0 to 14, with 7 being neutral. Ideally, pool water should be between 7.2 and 7.8. Below 7.0, the water is acidic; above 7.8, it’s alkaline.
Alkalinity (Total Alkalinity): This represents the water’s ability to resist changes in pH. It acts as a buffer. The ideal range for total alkalinity in a swimming pool is typically 80-120 parts per million (ppm).
Why are these parameters important? If the pH is too low (acidic), the water can corrode pool equipment, etch plaster surfaces, and cause skin and eye irritation. If the pH is too high (alkaline), it can lead to scale formation, cloudy water, and reduced sanitizer effectiveness. Low alkalinity causes pH to fluctuate easily (pH bounce), while high alkalinity makes it difficult to adjust the pH.
The Role of Soda Ash
Soda ash is a chemical compound, sodium carbonate (Na2CO3), that is alkaline. When added to pool water, it reacts to increase the pH and, subsequently, the total alkalinity. It achieves this by neutralizing acids present in the water, effectively raising the pH level.
Benefits of Using Soda Ash
Using soda ash to adjust the pH in your pool offers several benefits:
- Prevents Corrosion: By raising the pH, soda ash protects pool equipment and surfaces from corrosion caused by acidic water.
- Enhances Sanitizer Effectiveness: Proper pH levels allow chlorine and other sanitizers to work more effectively, killing bacteria and algae.
- Improves Swimmer Comfort: Balanced pH levels prevent skin and eye irritation, making swimming a more comfortable experience.
- Reduces Scale Formation: Though seemingly counterintuitive, raising the pH to the optimal range helps prevent scale formation that occurs with excessively high pH. Properly maintained alkalinity prevents the pH from drifting too high.
The Soda Ash Application Process
Applying soda ash to your pool requires careful measurement and distribution. Here’s a step-by-step guide:
- Test the Water: Use a reliable pool water test kit or take a sample to a pool supply store for professional testing.
- Determine the Dosage: Based on the test results, calculate the amount of soda ash needed to raise the pH and alkalinity to the desired levels. Always follow the manufacturer’s instructions on the soda ash product label. Many online pool calculators are also available to assist with dosage calculation.
- Pre-Dissolve the Soda Ash: Dissolve the calculated amount of soda ash in a bucket of water. Never add dry soda ash directly to the pool, as it can clump and be difficult to dissolve.
- Distribute Evenly: Slowly pour the dissolved soda ash solution around the perimeter of the pool. Avoid pouring it directly into the skimmer or near pool equipment.
- Circulate the Water: Run the pool pump for at least 2-4 hours to allow the soda ash to circulate and mix thoroughly.
- Retest the Water: After circulation, retest the water to ensure the pH and alkalinity levels are within the desired range. If needed, repeat the process, using smaller adjustments.
Common Mistakes to Avoid
- Adding too much Soda Ash: Overdosing can raise the pH and alkalinity too high, leading to cloudy water and scale formation. Start with small doses and retest frequently.
- Adding Dry Soda Ash Directly to the Pool: This can cause localized imbalances and make it difficult for the product to dissolve properly.
- Not Circulating the Water: Without proper circulation, the soda ash won’t distribute evenly, leading to inaccurate readings and uneven chemical balance.
- Ignoring Alkalinity: While soda ash primarily affects pH, it also influences alkalinity. Be sure to monitor both parameters and adjust accordingly.
Soda Ash vs. Other pH Increasers
While soda ash is a common choice, other products can also raise pH levels in pool water. These include:
| Product | Chemical Name | Primary Effect | Considerations |
|---|---|---|---|
| Soda Ash | Sodium Carbonate | Primarily raises pH; also increases alkalinity. | Widely available, effective, can raise alkalinity too much if overdosed. |
| Baking Soda | Sodium Bicarbonate | Raises alkalinity; has a smaller impact on pH. | Useful for raising alkalinity with minimal impact on pH. |
| Borax | Sodium Borate | Raises pH and alkalinity. | Can be used, but often less preferred due to different boron levels desired. |
Safety Precautions
- Always wear gloves and eye protection when handling soda ash.
- Avoid inhaling soda ash dust.
- Store soda ash in a dry, well-ventilated area, out of reach of children and pets.
- In case of skin or eye contact, flush immediately with plenty of water and seek medical attention if irritation persists.
Frequently Asked Questions (FAQs)
Why is my pool water pH always low?
- Consistently low pH can be caused by several factors, including acid rain, overuse of chlorine tablets (which are often acidic), and runoff from landscaping. Regular testing and adjustments are crucial.
How much soda ash do I need to add to raise the pH?
- The amount of soda ash required depends on your pool’s water volume and the current pH and alkalinity levels. Consult the product label or use an online pool calculator. As a general guideline, 1 pound of soda ash per 10,000 gallons of water can raise the pH by approximately 0.2 units.
Can I add soda ash and chlorine at the same time?
- It’s generally not recommended to add soda ash and chlorine simultaneously. It’s best to add soda ash first to adjust the pH and alkalinity, allow the water to circulate, and then add chlorine. This allows each chemical to work most effectively.
How often should I test my pool water’s pH and alkalinity?
- You should test your pool water’s pH and alkalinity at least twice a week. If you have heavy pool usage or experience significant weather changes, test more frequently.
What happens if I add too much soda ash?
- Adding too much soda ash will result in high pH and high alkalinity. This can cause cloudy water, scale formation, and reduced sanitizer effectiveness. You may need to use muriatic acid or dry acid to lower the pH and alkalinity back into the ideal range.
Is soda ash safe for all types of pool surfaces?
- Soda ash is generally safe for most pool surfaces, including plaster, vinyl, and fiberglass. However, always follow the manufacturer’s instructions and monitor the water chemistry to prevent imbalances that could damage the surface.
What are the symptoms of high pH in pool water?
- Symptoms of high pH include cloudy water, scale formation on pool surfaces and equipment, reduced sanitizer effectiveness, and skin and eye irritation.
Can I use soda ash to lower the alkalinity?
- Soda ash is used to raise both pH and alkalinity. To lower alkalinity, you would typically use muriatic acid or dry acid (sodium bisulfate).
Where can I buy soda ash for my pool?
- Soda ash is readily available at most pool supply stores, hardware stores, and online retailers that sell pool chemicals.
Is soda ash the same as washing soda?
- Yes, soda ash is essentially the same thing as washing soda. Both are sodium carbonate (Na2CO3).
How should I store soda ash?
- Store soda ash in a cool, dry, and well-ventilated area, away from moisture, direct sunlight, and incompatible materials. Keep it out of reach of children and pets.
How long does it take for soda ash to affect the pool water’s pH?
- The time it takes for soda ash to affect the pool water’s pH depends on the circulation and mixing. Generally, you should start to see results within 2-4 hours after adding and circulating the water. However, always retest to ensure proper balance.