Pool Care Pool Water Chemistry

How to Safely Add Muriatic Acid to Your Pool

Pool chemistry is always a priority during swimming pool maintenance. It’s necessary to keep the pool water alkalinity, chlorine, pH, and calcium hardness balanced to make your swimming pool swimmable at all times. Among the many things you can add to keep the pool water balanced is Muriatic Acid.

In this article, I will take you through everything you need to know about Muriatic Acid. I will discuss what it is, why and when to use it, and much more.

Read along!

What is Muriatic Acid?

For starters, Muriatic Acid is available as a diluted hydrochloric acid solution. It might come in many labels depending on the brand selling it.

You can buy Muriatic Acid at almost all home improvement stores near you. You can use it for various tasks, including heavy-duty cleanings like efflorescence, rust, and stain removal from concrete and bricks.

And as you might have guessed, Muriatic Acid is a standard product at pool supply stores. It’s used for multiple uses, including lowering high alkalinity, pool stain removal, and a water pH reducer.

How to Use Muriatic Acid in Pool

Most people often think the only chemical required during pool maintenance is chlorine. However, Muriatic Acid is as crucial as a sanitizer.

As aforementioned, muriatic acid uses are applicable in reducing pool water pH, alkalinity, and pool stains removal.

When you balance the pool chemistry but forget the alkalinity and pH, you risk your pool getting cloudy, chlorine insufficiency, and scaling. And the worst is, swimming in such a swimming pool can lead to eye and skin irritation.

If you have started getting skin and eye irritation after swimming, even when the chlorine levels are ideal, you might want to check your pool alkalinity and pH.

You can also use Muriatic Acid as a cleaning agent when cleaning your filter cartridge. It can help break down dirt build fast.

It’s also a perfect stain remover. You can use it to attack the rust stains off the pool surfaces and the grout between the pool tiles.

Note: Even though it’s a perfect stain remover, it’s too hard on vinyl liners. NEVER use it to clean vinyl pools but instead use a cleanser formulated for this swimming pool type.

Besides using it for cleaning and balancing, you can use Muriatic Acid in pool to kill algae. It can help kill any algae and mold leftovers in your pool water at the end of the year.

Its Acid’s stout acidity can help kill the stubborn algae growth. If you combine chlorine with Muriatic Acid for pools algae, the results are exceptional.

When Do You Use Muriatic Acid in Pool?

One of the primary functions of muriatic Acid is pool alkalinity and pH reduction. When you test your pool water, and the pH reads 7.8, your swimming pool isn’t balanced – it’s too alkaline.

High alkalinity in pool water can cause cloudiness, scaling, and an increase in calcium hardness. You might also notice an increase in algae blooms.

Even though high pool alkalinity might decrease by itself, it might take longer, or you might be tempted to ignore it.

If you wait too long, the damage to the pool surfaces, filtration, and circulation systems could be critical. Your pool sanitizer might be forced to work harder, resulting in chlorine insufficiency.

That’s why you should add Muriatic Acid, a cheaper and effective solution when you test your pool and notice it is high on pH and alkalinity.

How Much Muriatic Acid to Add?

Every swimming pool requires a different amount of Muriatic Acid depending on the water pH level and its capacity.

Before you can calculate the amount you need, know your pool’s exact water pH level. It can be tough to get consistent and accurate results when using standard test strips. They will tell you whether the pH is high or low, with no values.

The best solution would be to take a pool water sample to a pool testing point near you or use a digital pool water tester.

Most of the time, you’ll be required to add around a quart of muriatic Acid in an averagely-sized inground pool (around 15,000 gallons) if your water pH level is above 7.8.

After adding the Acid, allow the circulation to run for an hour and then retest the pH level.

If you have got a smaller above-ground pool, it’d be best to add a cup of Muriatic Acid. Retest the water pH to determine how much more Acid you have to add.

The idea is to reduce the pH level gradually as Murautic Acid makes the water more acidic. Highly acidic water could lead to metal corrosion, chlorine loss, and wrinkles to your pool vinyl liner.

Run your pool pump to circulate and aerate the pool water and nudge the pH levels upward gently.

Most Muriatic Acid brands provide a label to guide how many acids you need to add. But if it’s not available, you can get the figures from an online muriatic acid pool calculator.

How to add muriatic Acid to pool

Is everything about using Muriatic Acid to balance pool water clear now? I bet it’s. Now that you’re well versed, it’s high time we jumped into how to pour Muriatic Acid into the pool.

Step 1: Safety First!

Safety comes first, considering Muriatic Acid is highly acidic and adding it in pool water requires you to mix chemicals. That’s why you should wear the right, protective chemical-resistant gear.

If you handle the Acid without the protective gear, you risk burning your skin and suffering severe respiratory problems caused by the Acid’s vapor.

Here are the few things you will need to protect yourself when adding muriatic Acid in pool water:

  • Acid-resistant gloves
  • Chemical-resistant apron
  • Safety goggles
  • Plastic bucket
  • Stirrer (Wooden or Plastic)

Apart from the above safety necessities, you will also need Pool Water Tester to give you the exact level of your pool pH and alkalinity.

Step 2: Test Your Water

Before you can attempt to balance your pool pH and alkalinity, it’d best to check their accurate levels first. Get your digital pool tester and give it a test.

No matter how high the pool water alkalinity is, using Muriatic Acid to lower has to be done in stages. The whole process might be time-consuming, so spare your time for the task.

Step 3: Turn Off Water Circulation

Suppose you’re trying to lower the pool alkalinity while also trying to balance the pH. In that case, it’d be best to stop the water circulation by turning off the heart of the whole system, the pump, before you can add Muriatic Acid.

When the pool water is circulating, the water gets aerated through bubbling and churning. Exposure to oxygen can amplify the Muriatic Acid effects on the water pH.

If you want to lower your pool’s total alkalinity with a wide margin, it’d be best you reduce the water movement.

Step 4: Add Muriatic Acid

The best way to add Muriatic Acid in pool water is to dilute it first in a bucket to make the whole process straightforward and safer as it eliminates splashes.

That is, if you don’t, you might using a few extra minutes to mix it in a bucket. But if you’re in a hurry, you can pour it straight into your pool water.

As aforementioned, the perfect water to muriatic acid ratio is 10:1. Add the water first, pour the appropriate acid amount into the bucket and stir gently with the wooden or plastic stirrer.

Once everything is dissolved nicely, you can pour the bucket contents into your pool. If the pH readings were too high, it’d be best to walk around pouring the solution slowly and evenly.

That will add some oxygen to the water to improve the Muriatic Acid effects slightly and help distribute the chemicals.

Note: You MUST rinse the bucket you used to mix the Muriatic Acid thoroughly after use. Also, NEVER use it with any other chemicals as it could lead to a dangerous explosion.

Step 5: Allow the Acid to Work

You can take one of two approaches here. Play it safe and kick your pump to circulate the muriatic Acid for at least half an hour. This will help prevent the Acid from settling on the bottom of your pool and damage your pool surfaces.

It’s time to leave the Acid to act on the pool alkalinity and lower it to the possible point. You have two options here:

  • Turn the pump back on for an hour or
  • Leave the pump off and allow Muriatic Acid to lower the alkalinity.

Turning the pump on allows the water circulation to distribute the Muriatic Acid to all pool corners. It will make sure the Acid doesn’t settle on the pool bottom and cause damage to the floor surfaces.

Leaving the pump off is an approach known as pooling. The problem with this method is, Muriatic Acid caustic characteristics could eat your pool floors if left to settle.

If you decide to go with this approach, it’d be best to get a pool brush with a telescope for constantly brushing the pool floor. It will help prevent the Acid from settling and causing damage.

If you don’t see yourself spending an hour brushing your pool floor, then turn on your pool pump and allow the water to move, and do the work for you.

Step 6: Aerate Your Pool

As mentioned earlier, aerating your pool water when you have added the Muriatic Acid amplifies its effects. It helps prevent raising the water alkalinity when trying to increase the pool pH.

An easy way to manage pool aeration is to direct the return jets upward and set the pool pump speed to the highest.

If your pool has water features like a pool fountain, it’d be best to turn them on too. You can also take other drastic measures such as adding a pool aerator.

Step 7: Retest the Water

The morning after you add muriatic Acid to your pool, recheck the water chemistry. If your alkalinity hasn’t gone down far enough, you can add another dose of muriatic Acid.

After adding Muriatic Acid and aerating your pool water, you’ll need to retest your pool water chemistry. If the alkalinity is too far high, you can get another dose of muriatic Acid.

If the water pH is low but the pool alkalinity is balanced, continue aerating your swimming pool. After a day, retest the pool pH again and see if it’s balanced too.

If the pool pH is still low, you might need to give the Muriatic Acid an extra hand by adding a pool pH reducer. Remember, though, to use it in light amount.

How Long After Adding Muriatic Acid Can You Swim?

According to experts, it’s best to wait at least 15 minutes before dipping yourself in the swimming pool after treating it with Muriatic Acid.

If the pool water pH was too high and you had to add more than one dose of Muriatic Acid, you have to wait at least two hours before you can swim.

If you entered the pool after dosing it with more than one dose, you risk getting burned by the acid ‘hot spots.

That’s why it’s advisable to wait at least two hours before swimming after treating your pool water with any chemicals.

What Happens If You Have Too Much Muriatic Acid in Pool?

If you added massive amounts and now the muriatic acid level in your pool is too high, more than required, your pool water pH levels would go dangerously low.

With Muriatic Acid containing hydrochloric Acid in concentration, between 28 – 35 percent, it can be highly corrosive and irritating to your eyes and the respiratory system.

What’s more, acute exposure to the acid fume can cause inflammation, coughing, ulceration, and hoarseness of your respiratory tract.

What is the Best Substitute for Muriatic Acid in Pool?

Even though Muriatic Acid is the best in lowering water pH, there are other options you can go with. One of them is using pool sanitizers that do not affect the pool water pH or use different pool pH lowering products. They include:

a) Sodium Dichlor

Sodium Dichlor is available as a granular or tablet chlorine sanitizer. Its pH ranges from 6.8 to 7.0. It’s an ideal pH reducer for pools with a pH between 7.2 and 7.6.

The best way to add Sodium Dichlor to your pool water is by mixing it with water in a 5-gallon bucket and stirring it till it dissolves. Spread it as you walk around is also best to keep it evenly distributed.

For the tablet form, put them in an erosion feeder, floating feeder, or use a tablet chlorinator that you attach to the pool plumbing.

b) Trichlor

Trichlor is available in tablet form. It’s another practical chemical ideal for reducing pool pH. It has a very low pH, between 2.8 and 3.0.

Because of this, it’s perfect for reducing too high pool pH. You might occasionally, after using it, add a base, soda ash, or baking soda to increase the pH a bit.

Most of the Trichlor products contain cyanuric Acid, a perfect stabilizing agent ideal for blocking ultraviolet rays from breaking down chlorine.

The best way to add it to your pool is through a floating feeder or a chlorinator. You must NEVER put it into the pool skimmer as the low pH might react with the skimmer materials and cause damage.

c) Sodium Bisulfate

Sodium bisulfate is the next best substitute for Muriatic Acid in Pool. It’s at the time referred to as dry Acid. Unlike the above two, it doesn’t sanitize.

It’s available in crystal form similar to granules. It dissolves in water relatively fast. That means you can add it directly to your pool’s deep end or spread it on the surface.

It can help reduce fumes in other pH reducers, but you must keep it as dry as possible during storage.

It does also eliminate the spill and splash problems. The ideal storage is in a closed container. Handle it carefully since it’s highly acidic.

Can You Use Muriatic Acid in a Saltwater Pool?

Yes. Water pH is affected by lots of things the body waste that wash off into the pool. If your saltwater pool has a high pH, you can use Muriatic Acid to reduce it.

However, you must avoid pouring muriatic Acid in pool skimmer or other pool equipment as it might eat them away.


One of the many things that you must do during pool maintenance is pH balancing. Muriatic Acid has proven to be a cheaper and effective alternative to lowering pool pH. Keeping your water pH balanced eliminates skin rashes and eye irritation, of course, if you balance other chemicals too. One thing that you need to remember when engaging yourself in this pH-reducing task is a safety precaution. Muriatic Acid is highly acidic and could burn you or cause an explosion if mixed with other chemicals.

About the author

Sharif Miah

Hi! I'm Sharif, the founder of Globo Pool® and I have been working in the pool & hot tub industry for the last few years. I love to share my experiences with people & hope you are enjoying my information and lessons!

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