An acid wash is a rejuvenating process that strips away stubborn stains, algae, and calcium buildup from pool surfaces using a carefully diluted acid solution. It restores the vibrant, clean look of your pool when standard brushing isn’t enough. Think of it as a reset button for older or heavily stained pools.
Over the years, pool plaster can absorb minerals, dirt, and chemical imbalances. When regular scrubbing and chemical treatments fail to bring back that original bright finish, an acid wash is often the most effective solution to make your pool look brand new again.
How the Acid Wash Process Works
An acid wash is not a simple chemical treatment added to filled pool water. It is an intensive, physical cleaning procedure. The process begins by completely draining the swimming pool. Once empty, professionals apply a carefully mixed solution of water and muriatic acid directly to the plaster or pebble surface.
This acidic mixture actually removes a microscopic top layer of the pool’s finish. By stripping away this razor thin layer of plaster, it takes all the embedded stains, stubborn algae, and hard water deposits with it. After the acid has done its job, the surface is thoroughly scrubbed, neutralized with a base like soda ash to stop the chemical reaction, and rinsed completely before the pool is refilled.
Signs Your Pool Needs an Acid Wash
You should not use an acid wash as a routine cleaning method. It is a specialized treatment reserved for severe cases. You might need to consider this process if you are experiencing the following issues:
- Severe Algae Infestations: If your pool was left untreated for a long period and turned completely black or dark green, the algae roots may have embedded themselves deep into the plaster. If you are struggling with this, reading our guide on why your pool water is green can help you determine if an acid wash or a heavy shock treatment is the right next step.
- Heavy Calcium Scaling: Thick, crusty white deposits that do not respond to brushing are a sign of long term calcium imbalance. To keep this from happening again after your wash, check out our complete guide on how to prevent calcium scaling on pool walls.
- Widespread Metal Stains: Copper, iron, and manganese can leave ugly brown or green streaks on your pool surfaces. If you are noticing these discolorations, you can learn more about the causes by reading our expert guide to fixing metal stains.
Should You Hire a Professional?
Handling gallons of highly concentrated muriatic acid is dangerous. The fumes are toxic, and the liquid can cause severe burns to the skin and eyes. Additionally, leaving the acid mixture on the pool surface for even a minute too long can permanently ruin the plaster, making it rough and porous.
Because of these risks, we highly recommend hiring licensed professionals to perform an acid wash. If you are curious about the financial investment required for professional services, review our breakdown of the cost of pool cleaning services.
Keeping Your Pool Pristine After the Wash
Once the acid wash is complete and your pool is refilled with fresh water, you have a blank slate. The goal is to never need an acid wash again. Maintaining perfectly balanced chemistry and keeping contaminants out of the water is the only way to protect your newly restored surface.
To keep your water sparkling and prevent the buildup of metals and phosphates that cause stains and algae, drop the DualPool 2-in-1 Pool Clarifier into your skimmer basket. This cutting edge, self-dosing technology works continuously to remove suspended solids and heavy metals before they can stick to your fresh plaster. By using DualPool, you maximize efficiency, reduce manual maintenance, and enjoy a brilliantly clear swimming pool all season long.
Frequently Asked Questions (FAQ)
How often should you acid wash a pool? You should only acid wash a plaster pool once every five to seven years. Because the process removes a thin layer of the pool’s surface, doing it too frequently will wear down the plaster completely and force you to pay for an expensive resurfacing job.
Can you acid wash a vinyl or fiberglass pool? No. Acid washing is designed strictly for concrete, plaster, pebble, and gunite pools. Applying an acid wash to a vinyl liner will destroy the material instantly. Fiberglass pools also require specialized, non-acidic cleaning agents to prevent ruining the gel coating.
Does an acid wash remove black algae? Yes. Black algae is notorious for driving deep roots into porous pool plaster, making it nearly impossible to remove with standard brushing and chlorine. An acid wash strips away the top layer of plaster, effectively removing the roots and eradicating the black algae entirely.
How long does an acid wash take? The actual washing process usually takes a few hours, but you must also account for the time it takes to completely drain the pool beforehand and refill it afterward. From start to finish, the entire project typically takes two to three days.