How to Lower Your Pool’s Alkalinity Using Muriatic Acid

Just when you figure out how to test your pool water for the first time, you get the bad news. Alkalinity levels are too high. But you might not be entirely sure what alkalinity means, let alone how to fix it. Is high alkalinity unhealthy? Is it kind of scary to know you will be fixing high alkalinity with muriatic acid – which doesn’t exactly sound like a relaxing swim, does it?

What is Muriatic Acid?

If you’ve read elsewhere that muriatic acid is how to address alkaline imbalance, you’re on the right track. Acid refers to anything with a pH of 7 or less. That means everything from citrus fruit to vinegar, carbonated beverages, and baking powder and bleach count as an acid.

Acid is used for a variety of purposes but does the same thing: it cleans and removes one substance from another. Muriatic acid is a form of hydrochloric acid, but with more dilution and a pH level of 1-2.

Let’s back up a step and first consider what alkalinity means and why it’s one of the most important factors in maintaining your swimming pool. Then I’ll review how muriatic acid helps the problem, one step at a time.

What is Pool Alkalinity?

Alkali refers to the soluble salt of an alkali chemical element derived from earth metal, or in some cases, the ashes of plants. Alkaline either contains alkali or has the same properties, as well as a pH greater than 7. Scientifically speaking, any soluble base is an “alkali,” including sodium hydroxide, potassium hydroxide, and sodium carbonate.

Therefore, all water contains alkaline substances. That’s why “total alkalinity” refers to the measuring of alkaline substances within a body of water. As a general rule, the pool’s total alkalinity should measure between 80 and 120 parts per million.

It’s essential to know the alkalinity levels because these substances directly affect the water’s ability to withstand change. Alkaline substances inhibit a shift in pH and serve as a buffering component.

In simple terms, what happens when alkalinity levels go beyond 80-120?

Too high and you have an imbalanced pH level, which creates a problem with excess calcium. Too much calcium can damage the pool with side effects like scaling, clogged filters, and cloudy water.

Too much calcium in the pool can also cause skin irritation and itchy eyes for your family and friends.

On the other hand, too-low alkalinity can make it difficult to adjust the pH levels of the water, slowly turning the water acidic. As you might guess, acidic water is harmful to pool surfaces and expensive equipment.

The water will lose minerals and eventually start taking it from the liner, leaving behind visible and irreparable damage. Other effects include corrosion, staining, and greener water.

Swimmers will also experience much the same symptoms as before, burning or itchy eyes and skin.

While keeping up with alkalinity levels can be tiresome, practicing this maintenance can save your pool’s equipment and protect your family and friends. Every pool owner should check alkaline levels regularly, two to three times a week.

Why Does Alkalinity Rise and Fall?

Remember that everything that makes contact with the pool changes the pH over time. When sweat and body lotions from people enter into the pool water, the pH level increases. When new water comes through, or when pool owners shock the pool with chlorine, alkaline levels do increase.

When it rains, the pH level decreases along with alkalinity levels. Bodily fluids and other debris can also change alkalinity levels.

How Can Muriatic Acid Help?

If you’ve read elsewhere that muriatic acid is how to address alkaline imbalance, you’re on the right track. Acid refers to anything with a pH of 7 or less. That means everything from citrus fruit to vinegar, carbonated beverages, and baking powder and bleach count as an acid.

Acid is used for a variety of purposes but does the same thing: it cleans and removes one substance from another. Muriatic acid is a form of hydrochloric acid, but with more dilution and a pH level of 1-2.

Muriatic acid is a milder acid, making it appropriate for treating swimming pool water, as it will lower the total alkalinity and pH. What’s important to observe is that the chemicals you buy have the proper concentration of muriatic acid, specifically for treating swimming pools.

Muriatic acid also cleans pool surfaces and filters. When you add it to the water, however, you aim to adjust alkalinity levels as close to 125 ppm as possible. Use our pool alkalinity calculator to help you dial it in to the right level.

Alkalinity levels decrease by default, so it might always be a little higher than average. But when you lower alkalinity levels, you also lower pH. That means to maintain balance you must adjust pH to between 7.4 and 7.6.

Changing alkaline levels is not as easy as it seems at first glance, because you can sometimes create a pool of water that’s low pH and high alkaline. This situation frequently happens if you use 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 Use Muriatic Avid to Lower Pool Alkalinity

Now I’m going to listen step-by-step instructions for anyone that wants to try a DIY approach.

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. Target 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.

Step 3: Dilute the Muriatic Acid With Water in an Acid-Resistant Container

Your ratio of water to muriatic acid should be 10:1, and remember – always add water to the bucket first and then pour the muriatic acid in afterwards. 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

Just in case you must neutralize the acid or quickly remove it from your skin. Store it 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.

Step 6: Make Sure the Pump and Filter Stay Running During This Process

After applying the recommended dose, let the pool water alone so it can circulate. Aim for a two-hour break.

Step 7: Retest the ALK and pH Again

Add more muriatic acid if the numbers are still off to reach the proper levels of ALK. You can add slightly more while aerating, so the pH rises to normal levels.

Step 8: Adjust pH Accordingly and Return to Normal

If you can’t get the pH level back to normal in a few days (7.2-7.6), 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.

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!

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.

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