Ready for a new pool, without the cost of buying everything from scratch? Well, pool acid washing isn’t quite that. But it can sure bring your pool back to life. Pool acid washing is a process that removes a thin layer from pool surfaces, especially pool plaster, to eliminate tough stains and discoloration. An occasional acid wash can give gunite or concrete pools cleaner, fresher-looking pool floors and walls—in just a few hours, with no new plastering necessary.
Anyone can acid wash their pool themselves, but this is not the kind of task for the faint of heart—or the tight of schedule. Because acid washing involves handling, well, acid, it’s important to do it safely. With a few precautions, I’ll explain how to get an acid wash properly done. All it takes is a few steps, some easy-to-find gear, and a friend to help out.
Acid washing is especially useful for addressing staining caused by mineral deposits, algae, or chemical reactions that regular cleaning can’t remove. Got the patience to do this right? Read on to make your pool look as good as new. You’ll be glad you did.
When draining your pool for acid washing, remember that most pools have a hydrostatic valve to prevent uplift damage from hydrostatic pressure. This important feature helps protect your pool structure during the process.
Acid Washing What?
You heard me right. Acid washing your pool actually does involve an acid, specifically muriatic acid, to corrode the sides of your pool—and the stains left by chlorine, algae, metal, and other junk with it.
I know what you’re thinking: isn’t preventing corrosion one of the reasons it’s so important to keep the pool chemically balanced? Well, that’s exactly right. But acid corrodes evenly, and diminishes your plaster width by juuust a little bit—not so much that it compromises the structure of your pool, but enough that it reveals a fresh, vibrant, and clean layer.
Your same plaster, beautiful for longer. It’s a great deal. But because this is an acid we’re dealing with, it’s imperative to take an incredible amount of caution throughout this process.
Acid washing is only for inground pool types, and only those made of concrete and gunite. If you have a vinyl pool liner, this process just isn’t for you—which is totally okay, since once a vinyl liner really loses its life, all you have to do is replace it.
Has it been the right amount of time since you last had your pool acid washed, if ever? Are you starting to notice that no amount of scrubbing with even the most efficient brushes makes the plaster of your pool look clean? Acid washing will give your pool walls the reset they need.
It’s also a great way to recover a pool from sitting stagnant for a period of time. And in some cases, you don’t even need to acid wash the entire pool. If you’re making repairs for your plaster and have a spot of algae that needs to go before you add more, these steps for acid washing still apply—just with a smaller amount, and in a targeted area.
As an alternative, regular cleaning as part of your pool maintenance routine can help prevent the buildup of stains and algae, reducing how often acid washing is needed.
To drain your pool, you want a powerful, reliable, and heavy-duty submersible pump like the BLACK+DECKER 1500 GPH Automatic Submersible Pump. It works on its own to detect water up to 1/8 inch and comes with a whopping 30 ft discharge hose and 25 ft power cord.
When to Acid Wash Your Pool
Hey, there’s only so much plaster in your pool in the first place. To not erode your pool walls completely, it’s important to be careful about when to do an acid wash. Most pool experts recommend every five years.
If every five years seems too infrequent for the amount of stains that your pool amasses, it might be a good idea to troubleshoot metal stains, re-master achieving chemical balance, and increase the frequency with which you vacuum—or just get an automatic cleaner to do the job for you.
Another consideration that should be common sense, but just in case: don’t attempt an acid wash when you don’t have a lot of time. This is not a job to rush or for cutting corners. Rushing the process or working in bad weather increases the potential dangers, such as slips, exposure to chemicals, or other hazards around the pool area. And if it ends up being a rainy or windy day? It’s not the right time to do this.
Acid Washing Right Means Acid Washing Safely!
Read this section carefully—if necessary, more than once. Taking these precautions could be the difference between a safe and smooth acid wash and an unsafe event.
Always wear proper protective gear, including chemical-resistant gloves, safety goggles, and a suitable breathing mask, when acid washing a pool. This gear is essential to protect against chemical splashes, skin contact, and inhalation of toxic fumes. If you have trouble finding specific safety gear, such as women's chemical-resistant boots, check with specialty suppliers or online retailers.
Be aware that handling acids can release toxic fumes, so ensure the area is well-ventilated and always use a breathing mask designed for chemical vapors.
When choosing an acid, consider using acid magic as a safer, low-fume alternative to traditional muriatic acid. Acid magic is effective for pool acid washing and produces fewer fumes, but it still requires careful handling, proper dilution, and the same safety precautions as other acids.
Never mix acid with other chemicals, as this can cause dangerous reactions or release harmful gases. Always store acids and other chemicals separately and follow all safety guidelines to prevent contamination or safety hazards.
Wear the Right Fit
If inhaled, acid fumes can cause a range of respiratory issues. Since you'll be working closely with muriatic acid, it's important to wear a mask that is proven to block out these fumes.
And since acid isn't just corrosive to plaster, but skin, too, wear chemically-resistant gloves—not gardening gloves, or what you'd use to wash dishes. No way, no how. When you finish acid-washing your pool, you'll want to rinse off the gloves with them still on, and apply soda ash to neutralize any acid remaining on the fabric. Only once that's done and done properly are you ready to remove and store away your gloves.
Here's a scary fact: if it comes into contact with your eyes, acid can cause you to lose your vision. Yikes, right? That's why you should always wear safety googles—and safety goggles that actually fit you. Don't take them off before the acid is neutralized and put away, you've removed and stored away your gloves, and you've thoroughly washed your hands.
It's also important to wear the appropriate clothing for the job. That means long sleeved pants, a long sleeved shirt, and closed-toe shoes—ideally, chemically-resistant boots.
Note: If muriatic acid does get in your eyes, do not rub them. Wash your eyes for a minimum of 15 minutes with water, and then seek medical help immediately. If it gets onto your skin, wash your skin immediately and thoroughly, and keep the spot under running water for at least 60 seconds.
To prep for an acid wash, you'll want to scrub all debris from your pool walls and floors. Use the BLACK+DECKER 360-Degree Bristles Pool Brush to work better, faster. It was developed by longtime pool maintenance experts to prevent aches and pains associated with getting hard-to-reach corners.
Handle Acid Carefully
The best and safest way to handle acid is to do so very, very slowly. Pouring acid and setting down any container with acid in a deliberately slow way can prevent dangerous acid splashes. Keep any container of acid you’re not currently using tightly closed with a lid and in a protected place. When you’re done acid washing, store any remaining acid sealed tight and in a cool, dry place.
Many pool owners now use acid magic as a safer, low-fume alternative to traditional muriatic acid. Acid magic is effective for acid washing but still requires careful handling, including proper dilution, ventilation, and the use of protective gear.
You’ll also want to always dilute acid in the appropriate order. In order to get the right strength of acid for acid washing a pool, you’ll need to mix acid and water. Always add acid to water, not water to acid. That way, water is always the main component of the mixture. This will keep the acid mixture from gaining heat and boiling up over the container—in other words, becoming uncontrolled acid. I don’t need to tell you what kind of nightmare scenarios that can lead to.
Never mix acid with other chemicals, as this can cause dangerous reactions or compromise water quality after treatment. Always handle acids and other chemicals separately and with extreme caution.
Understand How Acid Works
Another safety point to consider is that acid corrodes over time. That means that if it comes into contact with your skin and isn’t properly washed, it will continue to eat away until it is. Whereas rinsing off an acid spot immediately can keep the burn minor, not acting quickly or thoroughly can lead to serious, dangerous burns.
The same goes for your pool. We’re about to use acid to intentionally corrode your pool walls, but if it sits for too long it can actually cause damage to the plaster. It must be rinsed away in order to stop working. When you do rinse it off from your pool, do so at least three times. It’s crucial to remove all acid residue during this process, as any leftover can lead to ongoing corrosion or pose safety hazards. Neutralizing the acid residue with soda ash is recommended to ensure complete safety.
Keep the acid from wearing away at your pool floors by constantly using a hose to draw it to the disposal area. Don’t use a hose with too high a pressure that it runs the risk of spraying acid where you don’t want it.
Have a Disposal Plan—Before You Begin
Before you start, know where all that acidic water is going to go. During acid washing, dirty water and a foamy puddle can accumulate at the bottom of the pool, both of which need to be properly neutralized and disposed of to prevent staining, surface damage, or environmental harm. After the acid wash, make sure to remove any remaining water from the pool to avoid potential damage. Even if the acid water has been neutralized with a solution, it can still be harmful to plants and animals. In this case, it’s best to check with your local water authority, as every city and municipality has its own restrictions for this process.
Final Words of Warning
Above all else, it's essential to follow the manufacturer's instructions that came with your muriatic acid. The cautions and steps outlined here are based on experience and know how, but we're not responsible if something does go awry. So read up on these tips, read up on what your manufacturer suggest, and, above all else, stay safe!
Get the Gear
Before you start the process of acid washing, make sure you have the following items on hand:
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A mask proven to block out acid fumes
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Safety goggles
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Chemical-resistant gloves
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Long sleeved shirts and pants
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Chemical-resistant boots
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Acid brush with a long handle
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Muriatic acid
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pH increaser (such as soda ash) for neutralizing acid after washing
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Powerful submersible pump with a power cord long enough to reach the deep end (without an extension cord)
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Drainage hose
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2 garden hoses with spray nozzles long enough to reach all areas of the pool
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A friend to help out
How to Acid Wash Your Pool—In Eight Steps
Ready to make it happen? Read these instructions in full before you begin. No surprises. Acid washing removes only a very thin layer of plaster, typically less than 1/4 inch thick, so it’s important to proceed with care.
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Prepare the Pool and Remove Valves
The first thing you’re going to want to do is completely drain your pool—but remember, the process for inground pools can be seriously harmful if not done correctly, thanks to the dreaded possibility of an inground pool pop-up. If you’ve never read up on how to prevent the inground pool pop-up, do that now before your drain your pool.
When draining, you’ll be removing the hydrostatic pressure valves located on the pool floor. Again, it’s important to do this correctly, so be sure to follow the correct, detailed instructions on how to drain your pool.
As the pool is draining, use the pool brush to remove any dirt and debris before they can dry. Then, hose down your pool walls and floors. Do this continually as the pool drains to both remove debris and to keep the pool’s plaster walls from heating up under the sun.
2. Replace Those Valves
Now that the pool is drained, it's time to replace those hydrostatic pressure valves you removed. This will prevent the acid mixture from seeping into the ground below your pool, and basically corroding your pool's foundation.
3. Dilute the Acid
If you haven’t yet put on your safety gear, now is the time—and remember, that means goggles that you aren’t going to take off until the acid washing is fully complete and you’ve cleaned everything back up.
In a watering can, prepare your acid mix by diluting equal parts of muriatic acid and water. As I outlined in our safety section, it’s an absolute safety essential to start with the water first, then add acid to water in small doses. You can use less muriatic acid depending on the state of your pool. The less acid, the less corrosion to your plaster. Keep in mind that some corrosion is what you want if your plaster is in bad shape.
4. Get Your Hoses Straight
Turn on two garden hoses and place the end of each hose inside the pool, one on each end. Don't put the spray nozzles on them yet, but you do want to keep the water running. You'll be using a lot of water to get this acid wash done safely.
5. Start the Acid Wash
This is when it gets real. Remember, pour carefully! Starting at the deep end near the drain, use a garden hose without the nozzle to wet down the surface before you add some of the acid mixture to it. Every time you pour the acid, you want it to hit a wet surface. That’s one of the reasons why it’s best to work in smaller sections throughout this process. The acid wash process is effective for various surfaces in and around the pool, including decks and patios.
That friend I mentioned you’ll want helping you? This is when they really come in handy. You want to pour the acid in a circular pattern, and have the friend behind you use the acid brush to scrub the mixture into the surface of the plaster. After letting the mixture sit for 30 seconds to a full minute, depending on how much you want the acid to work, attach the spray nozzle to the hose and rinse the area down. Then, add a few pounds of soda ash to neutralize the area. Then, rinse it off. Continue this process across the floor of the pool, ensuring the pool's surface is thoroughly cleaned and protected.
Next come the pool walls. Starting at the shallow end of the pool, wet the surface, add the acid mixture, let it run down the pool wall, and have your friend scrub it down behind you as you move ahead. Then, let the mixture sit for 60 to 90 seconds, and rinse it off. Add soda ash to the walls, and rinse it off.
6. Stay Safe Throughout the Process
As you work, there will be a basin of water that collects in your pool, which will include the byproduct of muriatic acid. But because of the soda ash you applied, this solution should be neutralized. It’s important to add soda ash to this solution as you go, just to be sure that it won’t lead to any accidents during the process. Two pounds of soda ash per 1 gallon of acid should be sufficient for the job, but be sure to check with your manufacturer’s instructions. Alternatively, baking soda can also be used as a neutralizing agent to ensure the solution is safe and to prevent damage to the pool surface.
7. Done? Dispose of the Acid Mixture Safely
Before disposing of the water that has collected at the bottom of your pool, test it to make sure that it is neutral—meaning the pH should test around 7.4 to 7.6. Then, hook up your submersible pump, ensuring that where it pumps to is in line with the rules and regulations of your local water authority. Proper disposal of pool water after acid washing is important to prevent environmental damage and comply with local regulations.
When you do pump out the rest of your water, you might notice some trouble spots, such as dirty patches of plaster. These areas may be due to staining from mineral deposits, algae, or chemical reactions. Simply repeat the acid wash process on these targeted spots with an extra-diluted acid mixture, so that it’s not as strong as the first mixture you used. Then, add soda ash and rinse the area again to neutralize any acid residue. Once all trouble spots are sorted out, make sure the water is again sufficiently neutralized and use your submersible pump to drain it out of the pool.
Next, rinse the entire pool down again. We’re about to fill it back up for swimming, and we don’t want any residual acid in the pool. Ensure all acid residue is thoroughly removed, as any remaining can continue to corrode your pool walls and floor, leading to irreversible damage. After this final and complete rinse, drain the water using your submersible pump.
8. Finish the Job
That’s it! Now you can refill your pool using those two garden hoses, ideally with clip-on filter nozzles to prevent metal stains. As you refill, monitor the water level to ensure it reaches the proper height for safe and effective pool operation. Make sure to rebalance your chemicals before you jump in. You’re done!
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Acid Washed Pool Maintenance
Once your swimming pool has been acid washed and is sparkling clean, the real key to keeping it in pristine condition is regular maintenance. Acid washing is a powerful way to restore your pool’s surface, but it’s not a substitute for ongoing care. To prevent the return of stubborn stains, algae, and mineral deposits, make a habit of brushing the pool walls and floor with a quality pool brush at least once a week. This helps keep debris from settling and stops algae before it can take hold.
Don’t forget to skim the surface daily to remove leaves and floating debris, and vacuum the pool floor regularly to keep dirt from building up. Using a garden hose to rinse off the pool’s surface after heavy use or storms can also help prevent stains and mineral deposits from forming. Pool owners should also keep a close eye on water chemistry—test your pool’s pH and alkalinity levels frequently, and adjust as needed to keep them in the recommended range. Balanced water not only protects your pool surface but also makes the swimming experience safer and more comfortable.
It’s also smart to check your pool equipment, like the pump and filter, to ensure they’re running efficiently. A well-maintained pump helps circulate water and remove debris, reducing the risk of stains and the need for another acid wash. If you notice any buildup or trouble spots, address them quickly with a pool brush and a targeted scrub. For best results, use a brush with nylon bristles to avoid scratching the pool surface.
By sticking to a regular maintenance routine—brushing, skimming, vacuuming, and monitoring your pool’s chemistry—you’ll keep your pool looking fresh and inviting, and you’ll extend the time between acid washes. Remember, a little effort each week goes a long way toward protecting your investment and ensuring your pool is always ready for a swim.
Troubleshooting and Repair
Even with the best maintenance routine, sometimes issues can pop up after an acid wash. If you notice stubborn stains or mineral deposits returning to your pool surface, don’t panic—there are solutions. Start by using a stain remover or a specialty product like Bio-Dex to target those tough spots. For particularly persistent stains, you might need to repeat the acid washing process, but do so with caution. Overdoing acid washes can wear down the very thin layer of plaster that protects your pool, so always try less aggressive methods first, like a pressure wash or power wash.
If you spot any damage to the pool surface—such as etching, rough patches, or unevenness—this could be a sign that the acid washing process was too harsh or not done correctly. In these cases, it’s wise to call in a professional pool company. They have the expertise and equipment to repair the surface and restore your pool to its pristine condition, while also ensuring the acid washing process is done safely in the future.
Equipment issues can also arise, especially if debris or acidic water has affected your pump or filter. If your pump isn’t working as it should, or if you notice reduced water flow, troubleshoot the equipment and make repairs as needed. Regular maintenance of your pool’s systems will help prevent these problems and keep everything running smoothly.
Always remember to follow safety precautions when dealing with acidic water or any pool chemicals. Wear protective clothing, use a garden hose to thoroughly rinse the pool surface after any cleaning, and never hesitate to seek professional help if you’re unsure. Acid washing should be a last resort for removing stains—try other cleaning methods first to prevent damage to your pool’s surface.
By staying vigilant, addressing issues promptly, and following a solid maintenance plan, pool owners can enjoy a clean, safe, and beautiful pool all season long. And if you ever run into trouble you can’t solve, don’t hesitate to reach out to a trusted pool company for expert advice and service.
Looking Fresh!
Consider this one of the more advanced pool DIY skills—and now it’s securely under your belt. Acid washing helps rid your pool of stubborn stains, algae, and mineral deposits, leaving the surface fresh and clean. Your pool will look fresh for years to come. And about five years from now, you’ll have no problem bringing it back to life again. For now, it’s probably time to get another pool party on the books—if only to show off that sparkling clean plaster!
This article explains how you can backwash your pool filter efficiently. Want to know how to clean the bottom of your pool? Read more!
