Should You Use Sulfuric Acid to Treat Your Pool?

Written by Michael Dean
September 14, 2023

sulfuric acid next to a swimming pool

Proper pool maintenance is at the core of every clear and sparkling pool. And every pool owner knows that the pH level plays a major role in ensuring the pool is safe and clean for swimming. While you may already be familiar with chemicals like muriatic acid or baking soda, sulfuric acid is one you may not know so well. 

In this article, I will explain how to use sulfuric acid to lower pool pH and alkalinity. I’ll also discuss the benefits and drawbacks of using sulfuric acid in your pool. So, let’s dive in!

Main Takeaways

  • Sulfuric acid is a potent mineral acid that can be used to lower pool pH and alkalinity levels.
  • Sulfuric acid requires careful handling due to its hazards.
  • The benefits of sulfuric acid include precise pH control and rapid dissolution.
  • Some of the drawbacks of sulfuric acid include its corrosive nature and potency.
  • Muriatic acid and dry acid are safer and more user-friendly alternatives for pool owners.

What Is Sulfuric Acid?

Sulfuric acid, or sulphuric acid, with the formula H2SO4, is a potent mineral acid used for many purposes, like manufacturing phosphate fertilizers, other acids, automobile batteries, dyes, glue, or wood preservatives.

It’s a colorless, odorless, viscous liquid that mixes well with water and is composed of sulfur, oxygen, and hydrogen. Sulfuric acid is used in various ways due to its reactivity and corrosive nature, including chemical production, metal processing, and even cleaning agents!

Should You Use Sulfuric Acid to Treat Your Pool?

While it isn’t commonly used in pools, you can treat a pool using sulfuric acid. Muriatic acid and dry acid are typically much more common, but you can also use sulfuric acid as an alternative to these chemicals in your pool.

Specifically, sulfuric acid is used in pools to lower both pH and alkalinity levels – just like muriatic and dry acids. If your pool’s pH is higher than the recommended range (generally 7.2 to 7.6), adding a calculated amount of sulfuric acid can help bring it back to the optimal level. Similarly, if the alkalinity level is too high as well, sulfuric acid can assist in reducing it to the desired range between 80 and 120 ppm.

Sounds simple enough, right? Well, you must use sulfuric acid properly and safely due to the high hazard risks. This chemical is HIGHLY corrosive and can be very dangerous if mishandled. So, let’s go over how to use it.

How to Use Sulfuric Acid to Lower pH and Alkalinity in Pools

Before even considering handling sulfuric acid, ensure you have the proper safety gear. This includes the following:

  • Chemical-resistant gloves
  • Safety goggles
  • Acid respirator mask. 

You should also work in a well-ventilated area; it is better to use sulfuric acid in outdoor settings.

Step-by-Step: Using Sulfuric Acid to Treat A Pool

Step One: Test the pH Levels

Test your pool water’s pH and alkalinity levels using a reliable testing kit. The ideal pH range is between 7.2 and 7.6 (or up to 7.8 at a push!). Based on the results, read the manufacturer’s instructions to calculate the amount of sulfuric acid needed to bring the pH down within the desired range. How much you add will depend on the pH of the pool, the volume of the pool, and the concentration of the sulfuric acid.

Remember, less is often more; avoid overdoing it. After all, you can always add more sulfuric acid if needed!

Step Two: Dilute the Acid

Sulfuric acid is highly concentrated and can be dangerously reactive. So, always dilute it before adding it to the pool. To do this, fill a bucket with water and carefully add the calculated amount of sulfuric acid – in this order. Never add water to sulfuric acid, as this can lead to a reaction known as chemical bubbling.

Step Three: Pour the Solution

Now, add the diluted sulfuric acid mixture slowly to the pool water. Start by pouring it along the perimeter of the pool while the pump is running. This will aid in even distribution throughout the pool.

Step Four: Retest the pH

After adding the acid, give it some time to thoroughly mix with the pool water. This typically takes a few hours. After the waiting period, retest the pH and alkalinity levels. If necessary, you can repeat the process to achieve the desired balance.

Benefits of Sulfuric Acid in Pools

So, what are some of the main benefits and arguments for using sulfuric acid in your pool?

  • Effective pH and alkalinity adjustment: You can easily adjust the pH and alkalinity levels of your pool with sulfuric acid, helping ensure the water chemistry remains within the recommended range for comfortable and safe swimming.
  • Readily available: Sulfuric acid is widely available in a wide range of concentrations, making it accessible for pool owners.
  • Cheaper: Sulfuric acid can actually be cheaper than even muriatic acid. Muriatic acid is around $30 per gallon, while sulfuric acid is around $25.                                                                                                                    

Drawbacks of Sulfuric Acid in Pools

But not everything is rainbows and sunshine. You should also be aware of the chemical’s cons.

  • Corrosive nature: Sulfuric acid is a strong acid with corrosive properties. Proper safety precautions, including wearing protective gear, handling in well-ventilated areas, and avoiding direct contact, are absolutely essential.
  • Adds sulfates: As its name may suggest, sulfuric acid adds unwanted sulfates to the pool. While low levels of sulfate aren’t an issue, long-term use of this chemical will add to the sulfate level to the point where it may be corrosive to your pool surfaces and equipment!
  • More dangerous to handle: Handling sulfuric acid requires care and precision. It is generally considered more dangerous to handle than muriatic acid or dry acid.

Other Types of Acids Used in Swimming Pools

While sulfuric acid is an option for treating pool water, other types of acids are commonly used in swimming pools. These include the following.

Muriatic Acid

Muriatic acid is by far the most widely popular and preferred choice for lowering pH and alkalinity. It is an incredibly effective acid that is less dangerous to handle than sulfuric acid. Plus, it is still relatively cheap, too, while not adding the dreaded sulfates to the water. This acid is used to adjust pH levels, reduce alkalinity, and clean pool surfaces. However, keep in mind that muriatic acid should still be handled with care and proper safety measures.

Dry Acid

Dry acid, or sodium bisulfate, is a granular acid generally considered more user-friendly than sulfuric and muriatic acid. It’s commonly used to lower pH levels and alkalinity in pool water. Although it works a bit more slowly, dry acid is generally safer to handle and store compared to liquid acids, making it a popular choice among pool owners. But note that dry acid will also add sulfates to the water.

Cyanuric Acid

Cyanuric acid is a bit different from the other acids listed here, as cyanuric acid is used to stabilize chlorine levels rather than pH and alkalinity. This chemical binds to the free chlorine in the pool to protect it from the sun. Think of cyanuric acid as a sunscreen that prevents chlorine from disintegrating under the sun’s UV rays.

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Frequently Asked Questions

Is sulfuric acid and muriatic acid the same?

No, these are two distinct types of acids used for pools. Both are used in pool maintenance to adjust pH levels and lower alkalinity; muriatic acid is also used to clean pool surfaces. Between the two acids, muriatic acid is generally the preferred chemical for pool owners, as it is safer to use.

How long after adding sulfuric acid can you swim?

After adding sulfuric acid to your pool, I recommend waiting at least 2 to 3 hours before swimming. This waiting period allows the sulfuric acid to mix thoroughly with the pool water and for the pH and alkalinity levels to stabilize. But before jumping in, always test the water first to ensure the water’s pH is at the recommended levels!

Use Sulfuric Acid Like a Pro

Although sulfuric acid is an effective chemical to balance pH and alkalinity levels in a pool, handle it with the utmost care! Due to its corrosive and dangerous nature, you must make sure you are taking appropriate protective measures to protect yourself and your pool. But when used correctly, it can be a cheap solution to a crystal-clear pool.

Do you have any more questions about sulfuric acid or other pool chemicals? Let me know!

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