Is your pool looking a bit dingy? Maybe you're dealing with some stubborn green, yellow, or black spots or streaks that have grown over time. These issues typically develop in pools that aren't properly maintained, and when they show up, they can be tough, if not virtually impossible, to get rid of.

No matter how hard you scrub or which chemical cleaning products you use, the staining and dingy discoloration might refuse to budge. So what was once a crystal clear, inviting pool now looks dirty, dingy, and distasteful. Fortunately, you can get rid of those stains and restore your pool's appeal with a professional service called acid washing.

What exactly is acid washing, and when should you have it done? Let's take a look.

What Is Pool Acid Washing?

Acid washing uses heavy-duty acids (usually muriatic and/or hydrochloric) to restore your swimming pool's visual appeal. Once applied, the acids effectively strip away a thin layer of plaster from the surface of the pool's walls, which doesn't harm the pool in any way.

Any stains or discoloration is ingrained in that layer of plaster, so when the plaster comes off, the discoloration disappears with it.

How Does Acid Washing Work to Clean Your Pool?

When a pool renovation specialist comes out to acid wash your swimming pool, they'll start by draining the pool completely. When the water is gone, they'll saturate one wall of the pool with water and then spray segments of that wall with acid.

Depending on your pool's staining, the spray may contain a blend of acid and other chemicals to help eliminate the discoloration. After applying acid to a segment, the technician will scrub the area vigorously with a special acid brush for about 30-90 seconds before thoroughly rinsing the area with water. This process will be repeated until the entire pool interior is clean. 

When Is Pool Acid Washing Needed?

Pool acid washing generally becomes necessary when a swimming pool has not been properly maintained or cleaned for some time. It may not be necessary at all for pools that are cleaned weekly and otherwise well-maintained.

Because acid washing removes a thin layer of plaster from your pool, it should not be done frequently. We do not recommend acid washing your pool annually, as too many treatments may necessitate re-plastering.

To help avoid the need for such abrasive pool cleaning, it's best to perform regular pool maintenance or hire a service to do it for you. Remember: An ounce of prevention is worth a pound of cure. You certainly want to protect and enjoy your investment, and regular cleaning will help you do that.

If you're dealing with the following issues, scheduling the service is probably a good idea:

Scale Buildup Caused by Hard Water

Hard water is high in several minerals that can accumulate on the walls of your pool over time, causing unsightly scale deposits and cloudy water. But these deposits do more than make your pool look bad.

The minerals they contain can affect the pH of your pool water, pushing it outside the optimal range. When that happens, the surface of your pool and various pieces of equipment can suffer damage if you don't address the issue promptly; acid washing will take care of the problem!

Algae Growth & Staining

Algae typically grow in pools that aren't cleaned often or thoroughly enough and those with long-term water chemical imbalances. Depending on the type, growths can be greenish-brown, yellowish, black, or even pinkish.

When these growths are promptly addressed, they may not cause staining at all. But if they're allowed to sit, getting off without heavy-duty measures like professional acid washing can be almost impossible. 

Check out What's Causing the Algae Growth in Your Pool? for more information.

Iron, Copper & Magnesium Stains

If you fill your swimming pool with well water, it probably contains iron and/or copper. And if the levels are high, your pool walls may develop brown, red, blue, green, or black stains over time.  

If your pool has this type of staining and you've tried to remove it without success, acid washing can quickly fix the issue. But once you have it done, you may want to consider filling your pool with water from a different source that isn't so high in iron. 

Got a few minor pool stains you're worried about? Learn how to identify, remove, and prevent pool stains to keep your backyard oasis looking great.

Can a Homeowner Acid Wash a Pool Themselves?

Although you can attempt DIY acid washing (supplies are widely available at retail pool stores), that doesn't mean you should.

Why not?

Because acid-washing chemicals are strong, they can be downright dangerous if you don't know how to use them properly or wear proper protective equipment. When inhaled, these heavy-duty acids can cause breathing problems, and if they make contact with your skin, they can leave behind painful burns.

Aside from its potential health hazards, DIY acid washing isn't a great idea because you could wind up damaging your pool. If you don't mix the chemicals properly or thoroughly rinse an area after scrubbing, the acid will continue eating away at your pool. 

Hiring a pro for the job is the safest way to go, especially when you choose our team at Royal Pool & Spa. Each team member has at least a decade of experience in the pool industry and can ensure your pool is properly handled.

Here's how we do it:


We use a pump to remove all of the water from the pool. We also remove any debris before beginning the wash process.

Mixing and Spraying

Next, we mix hydrochloric acid and various chemicals. We then spray an even layer of the acid solution on the surface of your pool's walls and floor.


Using the appropriate equipment and safety gear, we scrub the walls of your pool with the acid mixture still in place.


After we remove all buildup, we thoroughly rinse your pool to remove the acid. We may have to repeat this process several times to remove residual chemicals.

Get a Pool Acid Washing Quote in the Twin Cities

If your pool looks dingy or stained, let our Royal Pool & Spa team bring it back to life! We specialize in acid washing, comprehensive pool maintenance, pool repairs, and more, and we have proudly served pool owners in and around White Bear Lake for over 30 years.

To learn more about our services or get an acid washing quote, call us today at 651-779-7606 or request a quote online, and we'll get in touch with more information.