Acid Wash Pool Cost by Size (2026 Price Guide)
An acid wash pool cost typically runs $300 to $700 for a standard residential inground pool, with a national average near $450. Price scales with total surface area (floor plus walls, not just footprint), stain severity, and whether the crew has to drain the pool first. Small vinyl or fiberglass pools rarely need one at all.
That range holds for a straightforward plaster refresh. The number moves in either direction once you factor in stain type (metal stains cost more to strip than simple algae etching), regional labor rates, and whether draining and refilling is bundled into the quote. We break down the real math below, plus when to skip the acid entirely.
How much does an acid wash actually cost by pool size?
Cost tracks square footage of exposed plaster or gunite, not just the footprint printed on your pool’s spec sheet. A 12x24-foot pool runs $300 to $460 to acid wash, while a larger 20x40-foot pool runs $670 to $1,000, according to HomeGuide’s 2026 pricing data. Per square foot, contractors charge roughly $0.56 to $0.68, per Homewyse’s May 2026 cost calculator.
Here’s the surface area detail most estimates skip: an acid wash treats the pool’s total wetted area, which includes the walls, not just the floor. A pool that measures 400 square feet at the waterline can easily have 700 to 800 square feet of actual surface once you count the walls down to the floor. That’s why two pools with the same footprint can get different quotes.
How long does an acid wash actually take, start to finish?
A straightforward acid wash on a residential pool usually takes a crew half a day to a full day on-site, but the total downtime for the pool is longer once you count draining and refilling. Draining a typical 15,000 to 20,000-gallon pool can take anywhere from several hours to a full day depending on pump equipment, and refilling from a garden hose adds another day or two before the water level is back to normal.
Add curing time after that: plaster needs a few days of careful chemical balancing (brushing daily, holding off on full chlorine levels right away) before it settles into normal maintenance. All told, plan on the pool being unusable for anywhere from 3 days to a full week around a full acid wash, longer if the contractor is also patching or repairing plaster while it’s drained. That timeline is one more reason spring bookings fill up fast: nobody wants their pool offline for a week once swim season has already started.
What actually drives the price up or down?
Stain type is the biggest swing factor. Simple mineral scaling or light algae staining sits at the low end of the range, while heavy copper or iron staining (common after years of well-water fill or a failing heater anode) can push a job toward the high end or require a second pass.
Access and drainage matter too. If the pool has to be pumped down and drained before the crew can work, that’s a separate line item, often $200 to $600 depending on gallonage and whether the water goes to a storm drain or has to be trucked out. Some contractors quote acid washing and drain-and-refill as one bundled number; others itemize it. Ask which one you’re getting before you compare quotes.
Regional labor rates and travel distance move the number too, and a pool with heavy calcium scaling on the tile line often gets billed as a separate tile-acid job at the 1:4 acid-to-water ratio, distinct from the floor wash’s lighter dilution.
When do you actually need a full acid wash?
You need a full acid wash when the plaster or gunite has visible staining, scaling, or a dull gray film that a chlorine shock and brush won’t lift. This is a resurfacing-adjacent job, not routine maintenance. Vinyl-liner and fiberglass pools should never be acid washed; the acid will etch or dull the gelcoat and liner surface, and most manufacturer warranties exclude damage from acid treatment.
A lighter option exists for pools that just look dull rather than visibly stained: a “chlorine wash” or acid-brush spot treatment, done at a much weaker dilution, without a full drain. If your pool’s plaster is otherwise sound and the discoloration is patchy rather than pool-wide, ask your pool company whether a spot treatment gets you 80% of the result for a fraction of the cost and downtime.
Cost by pool size (the snippet-friendly version)
| Pool size (approx. footprint) | Estimated total wetted surface | Acid wash cost |
|---|---|---|
| Small, 10 x 20 ft (~200 sq ft) | ~400 sq ft | $225 to $270* |
| Standard, 12 x 24 ft (~290 sq ft) | ~600 sq ft | $300 to $460 |
| Large, 16 x 32 ft (~510 sq ft) | ~950 sq ft | $530 to $645* |
| XL, 20 x 40 ft (~800 sq ft) | ~1,450 sq ft | $670 to $1,000 |
*Rows marked with an asterisk are our own estimate, computed by applying the $0.56 to $0.68 per-square-foot rate to the wetted surface area. The 12x24 and 20x40 rows are directly sourced figures. Get a walk-through quote before budgeting off any table, ours included.
Can you acid wash a pool yourself, or is this a pro-only job?
Technically yes, but we don’t recommend it, and most pool companies will tell you the same thing. Muriatic acid is diluted hydrochloric acid, and OSHA sets a ceiling exposure limit of 5 ppm for hydrochloric acid vapor under 29 CFR 1910.1000, which is why professional crews work with the pump running, a respirator on hand, and the pool drained to a safe working level before they start.
The DIY math looks tempting on paper. A gallon of 31% muriatic acid costs $4 to $8 at hardware stores like Menards or Lowe’s as of 2026, and a full DIY kit (acid, neutralizer, brushes, PPE) can come in under $100 to $300 in materials. But that number doesn’t include the cost of redoing the plaster if you etch it unevenly, and it doesn’t include a hospital visit if the acid mixes with residual chlorine or splashes back. If you do go DIY anyway, dilute acid into water (never water into acid) at roughly a 10:1 ratio for a floor wash, keep the pump running for at least 30 minutes after application, and never work alone.
What happens if you get it wrong, or skip it when you need it?
Get the dilution or dwell time wrong and you etch the plaster unevenly, which shows up as blotchy or rough patches that no amount of brushing fixes; the only cure at that point is a full resurfacing job, which runs thousands rather than hundreds of dollars. Skip an acid wash when the plaster genuinely needs one, and staining tends to compound: metal stains oxidize further, rough etched plaster grabs algae faster, and the pool needs chemical intervention more often just to stay clear.
On the safety side, the CDC’s 2019 national surveillance data shows pool chemicals send more than 4,500 people to US emergency departments every year, with acid and chlorine mishandling among the leading causes. Most of those incidents trace back to mixing chemicals that should never touch, storing acid near chlorine products, or skipping ventilation and PPE. None of that is meant to scare you off a legitimate acid wash; it’s meant to explain why the quote includes labor for someone who does this daily, not occasionally.
Are there alternatives to a full acid wash?
Yes. If the plaster isn’t actually stained, most “the pool looks dull” complaints resolve with a heavy chlorine shock, a thorough brush-and-vacuum, and a few days of balanced water rather than acid. For pools between full acid washes, a partial drain-and-refill dilutes accumulated stabilizer and metals without the acid step entirely; expect $225 to $900 for a professional drain, clean, and refill, or as little as $2.50 to $9 per 1,000 gallons in municipal water costs alone if you’re filling it yourself, according to Angi’s 2026 pricing data. Tile-line scaling specifically can often be handled with a pumice stone or a small tile-only acid treatment instead of washing the whole pool.
How do you pick a pool company for an acid wash?
Ask for proof of license and liability insurance before anyone brings acid onto your property; a botched wash that damages plaster or a nearby deck is expensive to fix, and an uninsured crew leaves you holding that bill. A company that does acid washes regularly should be able to show you photos of a similar-sized pool before and after, not just describe the process.
Get the scope in writing: does the quote include draining, does it include neutralizing and disposing of the spent acid water, and does it include a final rinse and refill, or are those extra? Vague one-line quotes (“acid wash: $400”) are the ones most likely to grow once the crew is on-site and finds heavier staining than expected. A contractor who walks the pool first and prices based on what they actually see is a better sign than one who quotes over the phone from a size and a photo.
Timing matters too. Most companies book acid washes heaviest in spring, right before pool season opens, so a fall or winter booking (where the climate allows) can sometimes get you a better rate and a less rushed crew.
Bottom line
Budget $300 to $700 for a standard acid wash, more if the pool is large or the staining is heavy, and treat any quote under that range with the same scrutiny you’d give a quote well above it. Get a written scope (wash only, or wash plus drain and refill), ask what stain type they’re treating, and don’t attempt the acid step yourself unless you’re genuinely equipped for a corrosive chemical job.
FAQ
Does acid washing remove all pool stains? Not always. Acid washing lifts organic staining (algae, scale, general dullness) reliably, but deep metal stains from iron or copper sometimes need a metal sequestrant or stain-specific treatment first. A contractor should tell you upfront if your staining looks like a multi-step job rather than a one-pass wash.
How often should a plaster pool get acid washed? Most plaster pools need a full acid wash every 3 to 5 years, sometimes longer with consistent water balance and regular brushing. Acid washing more often than that thins the plaster faster than normal wear and shortens the surface’s overall lifespan.
Does acid washing shorten the life of pool plaster? Yes, incrementally. Acid washing removes a thin layer of the plaster surface every time, which is why it’s a periodic fix, not a routine cleaning step. A pool acid washed every year instead of every 3 to 5 will need resurfacing sooner than one washed sparingly and maintained with balanced chemistry between washes.
Do you have to fully drain the pool to acid wash it? Yes, for a full wash. Crews pump the water down to a low working level (not always bone dry) so the acid can be applied directly to exposed plaster, then hose and neutralize before refilling. Partial spot treatments on a patch of staining sometimes avoid a full drain, but a complete wash does not.
Is acid washing covered under a pool resurfacing warranty? Usually not, and doing it yourself can void the warranty outright. Most plaster and resurfacing warranties specify approved maintenance chemicals and dilution limits; an improper DIY acid wash is one of the most common reasons homeowners lose warranty coverage on a relatively new pool surface. Check your warranty terms before doing anything with acid on a surface under 2 years old.