Muriatic acid is a common chemical used in swimming pools to lower alkalinity levels in your pool water. You may have seen it in your local hardware store because you can use it for a variety of other projects around the house too. However, muriatic acid can help solve high alkalinity levels, lower pH levels, and more for your swimming pool too. I’ll cover all of that in the guide below, starting with what muriatic acid can do, then going over how to use muriatic acid, and finishing up with some FAQs. Let’s get started.
What is Muriatic Acid?
If you need to address an alkaline imbalance in your pool, then muriatic acid is where you should look. Acid refers to anything with a pH of 7 or less. Acids are found in citric fruits, vinegar, soft drinks, and even vitamins (many acids are also handy natural pool cleaners).
Acids can be used for various purposes, but pool owners use them for cleaning the surfaces and maintaining the proper pH levels when it comes to swimming pools. Muriatic acid is a form of hydrochloric acid that is more diluted with a pH level of 1-2.
Let’s now look at what alkalinity means and why it’s one of the most important factors in maintaining your swimming pool.
What is Pool Alkalinity?
All water contains alkaline substances. That’s why “total alkalinity” refers to measuring alkaline substances within a body of water. A swimming pool’s total alkalinity should measure between 80 and 120 parts per million as a general rule of thumb.
So what happens when alkalinity levels go beyond 80-120?
High levels create an imbalanced pH level, which can create a calcium-rich environment. Too much calcium can damage the pool with side effects like scaling, clogged filters, and cloudy water. It can also irritate the skin and eyes of anyone who enters the pool.
On the other hand, low alkalinity will make it difficult to adjust the pH levels of the water, turning the water acidic. Acidic water can also damage the pool’s surfaces and your equipment. And swimmers in this environment will experience similar symptoms to entering a pool with high alkalinity levels, i.e., burning or itchy eyes and skin.
While keeping up with alkalinity levels can be tiresome, it can save your pool’s equipment and protect your family and friends. Every pool owner should check alkaline levels at least two to three times a week.
Why Does Alkalinity Rise and Fall?
Anything that makes contact with a swimming pool will change the pH levels. These substances can include things like sweat, sunscreen, body lotion, or spilled drinks. When you add more water or shock the pool with chlorine, alkaline levels will increase. Rainwater will cause a decrease in pH levels and alkalinity.
What Does Muriatic Acid Do For a Pool?
There are two main uses for muriatic acid for pools. When muriatic acid is poured straight into your pool, it will help lower the pH levels and total alkalinity levels if they get too high. It is also a great tool to use with your brushes as it will break down stubborn algae or stains, and it will assist with freshening up the walls of your swimming pool.
How Can Muriatic Acid Help Lower Alkalinity and pH Levels?
To address an alkalinity imbalance, you will need to use muriatic acid. An acidic substance is anything with a pH level below 7. That means everything from citrus fruit to vinegar and even carbonated beverages are acids.
Acid has a variety of purposes, including cleaning the water and surfaces of swimming pools.
Muriatic acid is a milder acid, making it perfect for treating swimming pool water as it will lower the total alkalinity and even the pH level of the water. Be sure to buy chemicals specifically for treating swimming pools to have the optimal concentration of muriatic acid.
Alkalinity levels decrease over time and when you adjust the alkalinity you will also lower the pH levels. Keep your levels between 7.4 and 7.6 to maintain a balance.
Changing your alkaline levels is not as easy as expected. Sometimes you will create a pool of water that has low pH and high alkaline. This situation frequently happens if you use a chlorine stabilizer, which contains cyanuric acid.
For the best results, it’s best to adjust pH and alkaline levels in stages. Consider adding chemicals slowly, according to a paper on chemical adjustment.
Step-by-Step: How to Add Muriatic Acid to Your Pool to Lower Pool Alkalinity
Here is the step-by-step approach if you wish to attempt lowering your alkalinity by yourself.
Step 1: Test Your Total Alkalinity
Record the results using a pool water testing kit. Write down the target alkalinity. If the levels are too high, you must lower the pH. Your target level is 120 ppm. However, if you’ve noticed a recurring problem with high alkaline, go for a slightly lower target of 100ppm instead.
Step 2: Protect Yourself When Handling Acid
Undiluted muriatic acid is hazardous. Always use gloves and full-coverage clothing when handling. It’s also a good idea to wear eye protection.
Undiluted muriatic acid is hazardous. Always wear proper protective gear (gloves, eyewear, and full-coverage clothing) when handling the substance.
Step 3: Dilute the Muriatic Acid With Water in an Acid-Resistant Container
Your water to muriatic acid ratio should be 10:1, and remember – always add water to the bucket first and then pour the muriatic acid. If you pour the acid in first, you risk a chemical reaction.
Step 4: Keep Baking Soda Nearby, As Well as a Hose of Water
Baking soda is a perfect alkaline substance to neutralize the acid or quickly remove it from your skin. As an extra tip, be sure to store the acid as indicated and follow instructions on your local recycling center for disposal.
Step 5: Follow the Directions of the Test Kit
The instructions will explain to start with small doses of acid. Pour slowly to avoid spills or even splashes that could throw the numbers off.
The instructions on the kit will explain that you should start with a small dose and pour slowly to avoid spills or splashes that could throw the numbers off.
Step 6: Make Sure the Pump and Filter Stay Running During This Process
After applying the recommended dose, leave the pool water alone for around two hours to circulate.
Step 7: Retest the ALK and pH Again
Add more muriatic acid if the numbers are still off to reach the proper levels of alkalinity. You can add slightly more while aerating, so the pH rises to normal levels.
Step 8: Adjust pH Accordingly and Return to Normal
If the pH levels don’t go back to normal (7.2-7.6) in a few days, add small amounts of sodium carbonate for a manual increase.
Don’t lower the pH to the lowest value on the kit since this will deplete your pool pH levels. Make sure the pH is slightly higher than the lowest pH value, and try not to lower the pH all at once. Apply gradually, in stages, for accuracy.
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Frequently Asked Questions
How Much Muriatic Acid Do You Put in a Pool?
The amount of muriatic acid you will need to add to your pool depends on the pH level and the gallons of water your pool can hold. Our pool alkalinity calculator is a great tool for finding this amount.
Can You Pour Muriatic Avid Directly Into Your Pool?
Pouring muriatic acid directly into your pool can be dangerous because it will not be diluted. Doing this, you risk damaging concrete or pouring it on yourself. Just remember to fill the bucket with water before adding the acid. If you don’t, it can cause a chemical reaction.
Can Muriatic Acid Damage Your Pool?
Adding too much muriatic acid will lower the pH levels. If the pH drops too low, it can damage your pool equipment and even cause rashes or burns to anyone who swims in the pool.
When Should You Use Muriatic Acid In Your Pool?
Muriatic acid lowers the alkalinity of the pool. So if the pH levels are measuring above 7.8, then it may be time to add some muriatic acid.
Muriatic Acid vs. Hydrochloric Acid vs. Sulfuric Acid: What’s the Difference?
Muriatic acid and hydrochloric acid are actually the same chemical compound. The main difference between the two is that muriatic acid is less pure because it is diluted (around 20 percent). Sulphuric acid is a different chemical compound altogether that contains sulpher. Conversely, hydrochloric and muriatic acid contain chlorine.
Adjusting alkaline and pH levels is not easy at first, but it is a learning experience that will protect you and your pool investment for the long term. Follow the testing kit directions closely, and you will get the hang of it! If you’re uneasy about the safe handling of muriatic acid, try sodium bisulfate, which is a bit slower to take effect, but can still get the job done.
If you need to raise your pool alkalinity instead, read my complete guide on raising your pool alkalinity.
Curious to learn more about the proper chemical levels for your pool? Be sure to read our guide on pool water chemistry 101 as well. If you’re curious about learning how to use muriatic acid to clean your pool, read my guide on how to acid wash your pool.