Pool Acid Washing Removes What Brushing Cannot.
The stains are not sitting on the plaster. They are embedded in it. An acid wash takes that layer off and exposes fresh surface underneath.
What the Acid Actually Does to the Surface
A pool acid wash strips the top layer of your plaster using a diluted muriatic acid solution. That is not a metaphor. The acid dissolves a thin film of the plaster itself, taking the stains, calcium deposits, and algae residue embedded in it along for the ride. What remains underneath is clean, smooth, unstained surface that looks years newer.
This is why acid washing works when scrubbing, shocking, and enzyme treatments do not. Those methods clean what sits on the plaster. An acid wash removes the plaster the stains have bonded into. Mineral discoloration, iron marks, black algae roots that survived every chemical attempt: none of them survive losing the material they grew into.
We see the full range across Riverside County: white calcium scale from tap water that tests above 300 ppm, rust-brown iron stains from wells, stubborn algae shadows that outlast every shock treatment, and the flat gray film that settles in after years of direct sun exposure. Each one responds to acid. The question is whether acid is the right tool for your particular pool, or whether something lighter or heavier makes more sense.
Chlorine Wash, Acid Wash, or Start Over
Not every stained pool needs the full acid treatment. A chlorine wash uses a strong bleach solution instead of acid. It handles surface-level algae staining and light discoloration without removing any plaster material. If the staining is recent and mostly organic, a chlorine wash is cheaper, less aggressive, and usually enough. We will tell you if your pool qualifies.
An acid wash is the next step. It strips mineral scale, metallic stains, and deep-set discoloration that chlorine will never touch. Most pools can handle two to three acid washes over their lifespan before the plaster gets noticeably thin.
Past that point, the honest recommendation is a replaster. If the plaster is already pitting, delaminating, or showing exposed aggregate through worn spots, acid will make it worse. We check thickness and condition before we start any wash. If the surface cannot take acid safely, we say so upfront rather than collect a check and leave you with damaged plaster.
Send us a photo of the staining and we will tell you which treatment fits.
Request a Surface EvaluationSection by Section, Top to Bottom
The pool has to be fully drained before acid goes anywhere near the plaster. That alone takes planning. We time the drain so the shell is never sitting empty and dry in peak sun. Exposed plaster can crack in a matter of hours during a Riverside summer afternoon.
Once the pool is empty, we work in sections. Start at the top of each wall, apply a measured muriatic acid solution, scrub with a brush, and rinse before moving down. Dwell time is everything. Too short and the stain stays. Too long and the acid etches the plaster unevenly. Every section gets neutralized with soda ash before the rinse water reaches the deep end.
If you are combining this with a drain and restart, the two jobs overlap. We handle the drain, do the wash, and manage the refill and chemistry startup in one trip. That combination is the most common way we do this work, and it saves you the cost of draining twice.
All rinse water and acid runoff gets pumped out and neutralized. Nothing goes into the storm drain.
When We Will Talk You Out of It
An acid wash has limits. Every pass removes a thin layer of plaster, and pool plaster is not infinitely thick. On a pool that has been acid-washed twice before, a third pass risks exposing the gunite underneath. That means a rough, porous surface that stains faster than the plaster it replaced and feels like sandpaper under bare feet. At that point, the pool needs a replaster, not another wash.
We also decline when the plaster is already compromised. Cracks, hollow spots, delamination, or thin areas where the aggregate shows through. Acid makes all of these worse. If we drain your pool and find structural plaster damage, we will show you what we see and give you a realistic picture of your options. Sometimes the most useful thing we do on a job is explain why we are not going to do it.
200+ Neighbors Can't Be Wrong.
Join hundreds of satisfied pool owners across Southern California.
“Years of staining on our plaster and we thought we needed a full replaster. They acid washed it and the surface came back white. Saved us thousands.”
“Calcium scale had built up along the waterline and the walls felt rough. After the acid wash, everything was smooth and clean. Looked like a new pool.”
“We had leftover algae staining that regular cleaning could not touch. One acid wash and the plaster was spotless. Very happy with the result.”
“The pool had brown mineral stains all over the deep end. They drained it, acid washed the entire surface, and it came back bright white. Absolutely worth it.”
“We bought a house with a neglected pool. The plaster was stained and gritty. After the acid wash it felt smooth and looked like it had been freshly plastered.”
“Iron staining from well water had left ugly rust marks everywhere. They acid washed it and every stain came off. Pool looks brand new again.”
“Years of staining on our plaster and we thought we needed a full replaster. They acid washed it and the surface came back white. Saved us thousands.”
“Calcium scale had built up along the waterline and the walls felt rough. After the acid wash, everything was smooth and clean. Looked like a new pool.”
“We had leftover algae staining that regular cleaning could not touch. One acid wash and the plaster was spotless. Very happy with the result.”
“The pool had brown mineral stains all over the deep end. They drained it, acid washed the entire surface, and it came back bright white. Absolutely worth it.”
“We bought a house with a neglected pool. The plaster was stained and gritty. After the acid wash it felt smooth and looked like it had been freshly plastered.”
“Iron staining from well water had left ugly rust marks everywhere. They acid washed it and every stain came off. Pool looks brand new again.”
Where We Offer Pool Acid Washing
We provide pool acid washing throughout our Inland Empire and Orange County service area:
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