Sodium Bisulfate for Pools: Everything You Need to Know



As a diligent pool owner, your goal is to keep your pool clean, sparkly, and safe. Keeping all of the chemicals balanced in your pool can be a tricky business but doesn’t have to be a full-time job. 

It can be overwhelming but we’re about to make your life a lot easier. Stick to the fundamentals: pH and water alkalinity. These two measurements are the foundation for chemical harmony in your pool.

High pH and water alkalinity are two common issues when it comes to everyday pool care. Both of these issues can be solved with a sanity-saving supplement called sodium bisulfate. 

What is Sodium Bisulfate?

Sodium bisulfate, also known as sodium hydrogen sulfate is an acid that forms when sulfuric acid is combined with a sodium base, like sodium chloride or sodium hydroxide.

As you probably know, when you mix acids and bases, the result is generally a neutralized solution of the two. In this case, however, the sodium bisulfate is only partially neutralized and still maintains a very acidic pH of around 1.

Sodium bisulfate goes by many names. You may have heard it called bisulfate of soda, monosodium hydrogen sulfate, sodium hydrosulfite, sodium acid sulfate, dry acid, acid salt, and sulfuric acid sodium salt. Other, less obvious names are nitre cake or niter cake.

It has the chemical formula: HNaO4S and is used in a variety of household products as a cleaning agent, pH adjuster, fungicide, herbicide, or anti-microbial agent. When it comes to pool care, sodium bisulfate is an acidity regulator that is used to lower the pH and total alkalinity of your pool water.

Fun Facts About Sodium Bisulfate:

  • It’s an acidic salt
  • It’s very water-soluble
  • It has a low density
  • It decomposes when introduced to water
  • It’s generally stable
  • It’s corrosive to metals and tissue

Sodium bisulfate comes as a white, grainy crystalline solid that dissolves easily in water and can be stored and used as needed. It might not be something you’re familiar with in your everyday life but is a total lifesaver when your pool chemicals are out-of-whack.

Why You Need it in Your Pool

Keeping your pool clean, clear, and sparkling is the most important part of pool maintenance. Chlorine is, by far, the most powerful weapon in your pool care arsenal to accomplish this. However, chlorine won’t be able to do its job properly if your pH or water alkalinity levels are unbalanced.

Using sodium bisulfate in your pool helps to keep these important measurements at their correct levels, preventing cloudy water, halting corrosion of pool equipment, keeping your pool water free of bacteria and microbes, and basically helping your chlorine to live its best life.

The Importance of pH and Alkalinity in Your Pool Water

It all comes back to chlorine. Without a strong and effective sanitizer, no one is going to want to swim in your pool. It might turn cloudy, start to grow all kinds of exotic algae, and worst of all, if you did decide to take a dip in an unsanitized pool, it could get you and your family really sick.

Unbalanced pH and alkalinity levels confuse chlorine. When these factors are not where they’re supposed to be, they send all kinds of mixed signals to your chlorine, causing a chaotic mess of incompetence all around. You’re paying good money for these chemicals and they need to be doing their jobs, dammit.

The pH and alkalinity of pool water go hand-in-hand. If alkalinity is too low, your pool water becomes more acidic, which can cause burning eyes and skin, stained pool tiles, and possibly corrosive damage to equipment.

Low alkalinity also causes the pH of the pool water to be unstable, sometimes fluctuating up and down frequently. When this happens, your sanitizer gets confused and loses all efficacy. The chlorine molecules actually break down faster, leaving you with cloudy pool water, corroded equipment, and irritated skin and eyes.

The pH of pool water is already an unstable factor whose mood swings can cause you a whole host of problems. Can you guess what works best to stabilize pH? Yep, you guessed it… accurately balanced alkalinity. 

The moral of the story is that if your pH or alkalinity levels are off, your chlorine will not be able to work the way it’s supposed to. This is where sodium bisulfate comes in to save the day. 

Alternatives to Sodium Bisulfate

The main alternative to sodium bisulfate is muriatic acid, also referred to as hydrochloric acid, but actually contains only roughly 32% hydrochloric acid. Muriatic acid is a very strong acid that comes as a liquid and is readily available wherever you purchase your pool care goods.

Muriatic acid, like sodium bisulfate, helps to keep your pool chemicals balanced and is also used to clean tiles, remove mold and rust stains, and dissolve calcium deposits that may have built-up over time.

Both of these chemicals have the same effects on pool water when used correctly. The only byproducts of muriatic acid are salt and water, and it leaves little to no residue in your pool, whereas sodium bisulfate can cause a buildup of sulfates as time goes on.

Chances are, if you own a pool, you are going to be using one of these useful chemicals to keep your pool clean, your pH and alkalinity at the right levels, and your chlorine working efficiently. 

Safety Considerations

Sodium bisulfate is by far the safer option of the two. It is not dangerous to handle, where muriatic acid in its liquid form requires the use of acid-proof gloves, boots, and facial masks. Not surprisingly, the possibility of spillage is higher with a liquid chemical in general.

Sodium bisulfate is safe for the environment and is biodegradable. The US Food & Drug Administration has labeled sodium bisulfate as safe for humans and it is not classified as a hazardous material under DOT/OSHA. It has also been approved for use by the authorities of Mexico, Canada, New Zealand, Australia, and the EU.

How to use Sodium Bisulfate to Lower pH

The only way to know if you need sodium bisulfate in your pool is to test the water chemistry. As a conscientious pool owner, you know that testing often is the key to a clean and shiny pool. 

Step 1: Test

So, before you do anything, test the levels of the chemicals already in your pool. That’s Step 1. Ideally, your pool’s pH should always stay between 7.2 and 7.6. If your pH falls in this range, you’re good to go! If it’s higher than 7.6, however, it’s time to re-balance.

Step 2: Decide How Much to Add

How much to add depends on the results you got in Step 1. Read the manufacturer’s instructions carefully and add three-quarters of what is recommended. It is very important not to add too much.

Step 3: Dissolve First?

Some manufacturers recommend dissolving the sodium bisulfate in water first before adding it to your pool. Others suggest diluting it before adding. This is where the skills you learned in Kindergarten will come in handy. Follow directions.

Step 4: Add the Sodium Bisulfate

Sodium bisulfate comes in powder form so make sure to avoid working with this chemical if it happens to be a windy day. It’s acid after all, so getting on your clothes or skin could be quite damaging.

Make sure to pour the powder (or mixture) into your pool near the jets and not near the intake/skimmer (for an inground pool) and around the walls of the pool (for above ground pools). This will give the product more time to dissolve into the water and spread around evenly.

Step 5: Wait a Bit

Now it’s time to give the sodium bisulfate time to do its job. Go make some coffee or read a magazine. Cross off some items on your to-do list. You want to wait about 6 hours before retesting the water or getting in the pool. Don’t do it. Don’t even look at the pool.

Step 6: Retest the pH of the Water

Okay, now that you’ve waited 6 hours… it’s been 6 hours, right? Okay good. Now you can retest the water and check the pH levels. If your pool water is balanced correctly, you’re all set! If the pH is still too low, go back to Step 2 and add the other quarter, rinse and repeat.

How to use Sodium Bisulfate to Lower Alkalinity

Using sodium bisulfate to lower alkalinity in your pool is going to be roughly the same process as lowering the pH as we talked about above. If you find that your alkalinity is too low when you tested your pH earlier, you can kill two birds with one stone. (Why anyone would want to kill two birds is beyond me, though.)

As a general rule, your pool’s alkalinity should be between 80 and 120 ppm (parts per million). First, you’ll want to test your pool water to see if the chemicals are in the proper range. If your alkalinity is higher than 120 ppm, it’s time to add some sodium bisulfate!

Repeat the steps above, except this time:

  1. Turn the jets off if you have an inground pool.
  2. Add the sodium bisulfate slowly so as not to disrupt the pH balance.
  3. Wait another 6 hours before you retest.

Congratulations! Your pool is balanced! 


Despite the challenges, having a beautiful backyard pool is one of the most fun and rewarding gifts you can give to your family and friends. Now, keeping your pool clean and balanced just got a lot easier.

With proper pool water chemistry, your chemicals work more effectively, lasting longer and saving you money. Now grab your raft and revel in pool water perfection.

Categories: Pool Care, Pool Chemistry