How To Use Sodium Bisulfate In Your Pool & Everything You Should Know About It

Written by Michael Dean
August 31, 2023

buckets of sodium bisulfate

So you have a swimming pool that you have worked hard to maintain, keeping it clean and safe for anyone who wants to take a dip. Although your maintenance skills are on-point, lately, something just seems a little off. Maybe it has become a little too cloudy. Or perhaps you don’t feel like your chlorine is doing its job.

If you have heard that sodium bisulfate is the key to making – and keeping – your pool healthy, here is everything you need to know.

Main Takeaways

  • Sodium bisulfate is also referred to as dry acid or acid salt.
  • Muriatic acid is an alternative to sodium bisulfate, but it is more dangerous to handle.
  • You should use sodium bisulfate to lower the pH and alkalinity of your pool.
  • Wait at least 6 hours before jumping back into the pool after adding sodium bisulfate, and make sure to check the pH and alkalinity levels of the pool before you do so.

What is Sodium Bisulfate?

Not to get too technical, but sodium bisulfate is the product of sulfuric acid with a sodium base (such as sodium hydroxide or sodium chloride). If you don’t recognize its name, perhaps you know it by one of its others. Sodium bisulfate is also referred to as:

  • Sodium hydrogen sulfate
  • Dry acid
  • Acid salt
  • Bisulfate of soda
  • Monosodium hydrogen sulfate
  • Sodium acid sulfate
  • Sodium hydrosulfite
  • Sulfuric acid sodium salt

Here’s sodium bisulfate listed as “dry acid” at my local Leslie’s pool supply store.

As you can see from the ingredients list, it’s pretty much all sodium bisulfate.

Leslie's Dry Acid

You can get Leslie's Dry Acid (sodium bisulfate) online if you don't have a Leslie's Pool Supplies store near you.

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Believe it or not, sodium bisulfate is used in more ways than you might realize. For instance, you can find it listed on the ingredients label of foods because it is a commonly used food additive.

Sodium bisulfate is also found in household cleaning products, disinfectants, fungicides, herbicides, and tanning lotions. It is also used in meat processing, dietary supplements, and certain over-the-counter and prescription drugs.

Perhaps most importantly – and why you are here – is that sodium bisulfate is known for its ability to control the pH levels in swimming pools.

Muriatic Acid: Alternative to Sodium Bisulfate?

Many people who are familiar with how to maintain a pool have heard of muriatic acid. This acid is also used to lower the pH and alkalinity levels of pools. And it does just as good of a job (you can read my article on what does muriatic acid do for a pool for more information).

But is it an excellent alternative to sodium bisulfate? Which is the better choice?

Both chemicals can get the job done, but one is a bit safer to handle than the other. You see, muriatic acid is dangerous. It can very easily burn the skin and the surface of your pool. It should never be handled without proper eyewear, mask, and gloves. In addition, this acid comes in liquid form, making it even easier to spill or splash on accident while leaving burns on anything it comes in contact with.

Muriatic acid does work faster at stabilizing the pH and alkalinity levels, but it is not necessarily worth the risk for all pool owners. Sodium bisulfate may work a little slower, but it is a much safer and more user-friendly option for taking care of your pools.

When is it Appropriate to Use Sodium Bisulfate in Your Pool?

Your goal as a pool owner is to maintain a healthy pool that is clean and clear. It’s the most important part of your pool’s maintenance. After all, nobody enjoys a cloudy or green pool with algae.

Chlorine is likely your go-to source for keeping your pool cared for. But, sometimes, it needs a little extra help. You know, something that will help make the chlorine’s job a bit easier. Because if I know one thing, chlorine won’t do a pool any good if its levels are not balanced.

When the pH and alkalinity levels in a pool are off, the surfaces and pool equipment may be subjected to corrosion or buildup. The water itself will become cloudy and unhealthy in appearance. And choosing to swim in these conditions could lead to strong irritation of the skin and eyes. This is because the unlevel conditions break down the chlorine molecules much faster, leaving your pool susceptible to all sorts of things.

Sodium bisulfate to the rescue! Using this as a chemical to keep your pool’s pH and water alkalinity levels balanced can allow the chlorine to do its job – the way you intend it to. A properly chlorinated pool will not cause any building or corrosion, it should be safe to swim in, and you will have clear water free of nasty bacteria.

So, when should you add sodium bisulfate to your pool? Now! Sure, if your pool is screaming for help, there is a good chance adding it to your pool maintenance routine could help tremendously. But, there is no need to wait until there is an actual pool emergency to start using sodium bisulfate.

How to Lower pH with Sodium Bisulfate

If you are ready to incorporate sodium bisulfate into your pool care regimen to lower your pool’s pH levels, then you have to know the steps to take.

Test the Levels

First, knowing your pool’s pH level is important so that you know just how to treat it. Buy a pool testing kit at your local pool supply store, discount outlet, or even online. This kit should come with liquid or strips that help you determine your current pH level.

Now, test your pool water. Your pool should have a pH level between 7.2 and 7.6 for optimal conditions.

Read the instructions on how to use the kit to get your pH level. If it falls within the ideal range, there is nothing more to do at this time. However, if it is above 7.6, you will need sodium bisulfate to reduce it.

How Much Sodium Bisulfate to Use

There will be instructions on the test kit to keep your pool healthy. If your pH level is about 7.6, it should tell you, based on how high it is, just how much sodium bisulfate you should use.

Tip: Never use the total recommended amount. Start with ¾ of the suggested amount and then re-test later. Why? Adding too much can unbalance your pH levels in the other direction.

Time to Add the Sodium Bisulfate

Sodium bisulfate in its most common powder form should be added to the pool closest to the return jets so you can evenly spread it throughout the pool in a matter of minutes. For above-ground pools or those that don’t have jets, add the sodium bisulfate powder along the pool’s wall.

It is easy to tell when the powder has dissolved because it will no longer be visible.

Now, Wait – Then Re-Test

It takes time for sodium bisulfate to start working. It is an excellent solution but is not instantaneous. It may take a minimum of 6 hours to get the job done, so be patient — and stay out of the water.

Once your time is up, you will want to retest the water’s pH levels using your testing kit. If needed, add more sodium bisulfate.

How to Lower Alkalinity with Sodium Bisulfate

As you test your water’s pH levels, you should also check its alkalinity, especially since lowering the pH levels will ultimately lower the alkalinity.

Test Your Alkalinity Level

Using your kit, test your pool’s alkalinity. You are looking, ideally, for a number that falls between 80 and 120 parts per million. If it is higher than 120, adding sodium bisulfate will help.

Adding the Sodium Bisulfate

Follow the instructions, just like you did above, and only add ¾ of the recommended amount. This time, though, you will add it a bit differently (if you have an inground pool). Rather than using the jets to distribute it, turn your jets off.

Slowly add the sodium bisulfate and wait at least 6 hours before retesting.

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Safety Considerations

Although sodium bisulfate is relatively safe and approved by the US Food & Drug Administration as safe for humans, you should still take a few precautions.

  • Never enter the pool immediately following the addition of sodium bisulfate to your pool. Instead, wait a minimum of six hours. Then, retest and make sure the pool water has a safe pH and alkalinity level before swimming.
  • Adding sodium bisulfate to your pool should never be done carelessly. It should be a slow, monitored process. Not measuring and adding even a little too much can swing your levels in the other direction. It can be hard to find balance this way.
  • It should be noted that adding too much sodium bisulfate can cause damage to the surface of your pool, as well as damage to the plumbing.

Final Thoughts

Getting your pool water chemistry levels even and balanced may take time. You could test your waters, add sodium bisulfate once, and wait and retest for perfect results. Or, you could find yourself playing a back-and-forth balancing game just trying to find the ideal levels.

Questions about using sodium bisulfate? Let me know; always happy to help.

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