How To Acid Wash A Swimming Pool (step-by-step)

by T. Duff on April 27, 2009

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Here’s What You Need To Know If You’re Planning On Doing An Acid Wash To your Swimming Pool.

Sidenote: An acid wash should not be administered to a vinyl or above ground pool. :)

Who can do this? Anyone who’s willing to get a little dirty.  This can be done by pool owners who are looking to save a few bucks – there is labor involved.  Make sure you wear jeans, protective boots, goggles, rubber gloves and a respirator – the acid fumes can be very strong. This is not something to take lightly.

An acid wash is also called a drain and clean or an acid bath.  An acid wash becomes necessary if the pool has become a black lagoon (can often happen if winterizing has not been completed properly).  This is also a great way to eliminate/reduce staining.

What an acid wash really does: The purpose of an acid wash is to remove a very fine layer of the pool surface – bringing out a “new” coat.  When done properly, an acid wash can really make the pool surface look near new again.

A general rule of thumb for determining the need for an acid wash is if you can see the bottom of the pool, most of the time, you can bring it back to life with chemicals, some elbow grease and adequate filtration/circulation. If the floor is not visible, the cost of the chemicals and labor will generally be greater than the acid wash charge, and take quite a bit longer. Also, extensive and repetitive algae problems will stain plastered pools, making an acid wash the recommended route to take.

An acid wash is, put simply, purposeful stripping of a tiny layer of plaster, exposing fresh plaster beneath. One should not do this every year. If you have consistent staining – there’s something taking place in the chemistry (test for metals, TDS and calcium counts in the water). Most plaster coats (whitecoat or marcite) are in excess of 1/2″, so a few careful acid washes should not hurt.

If the staining is very light you may want to consider doing a pressure wash or a very light acid wash (consider 3 parts acid/1 part water – do a small area and see how it looks).

You may also decide on an acid wash not because of swamp conditions, but just to bring out a brighter, whiter finish. Mineral stains and/or deposits, chlorine stains, even dirt stains…an acid wash is always a dramatic aesthetic improvement.

If your pool has had years of algae blooms, and if your pool seems to grow algae overnight or just bloom very easily….changing the water and acid washing the surfaces algae sticks to can give you an algae free summer.

Be extremely careful in working with muriatic acid. Pool technicians and professionals are specially trained in its application and wear protective clothing and breathing apparatus during the acid wash. To protect our environment, the acid/water waste should be neutralized with soda ash prior to its being pumped to a safe location.  You can (and should) have the soda ash at the bottom of the pool to immediately neutralize the acid as it flows down during the wash.

Phase 1 to an acid wash: As you drain the pool, wash it down (scrub if necessary) to remove all algae, leaves and any other debris.

Phase 2: When the pool is clean and empty, you can begin to acid wash the plaster. Put on protective clothing and rubber boots, goggles and wear a breathing mask designed for acid fumes.

Phase 3: Proper mixing of the acid.  Add 1 gallon acid to 1 gallon water in a flower watering can.  Always add the acid to the water – NOT water to acid.  Wet down the wall with a hose. Keep the hose(s) running at all times, without a nozzle on it. Pour the acid/water mixture down the wall, from top to bottom, one 5-10 foot section at a time.

Do not allow the acid to sit on the plaster for very long. Usually 30 seconds is plenty sufficient. Use an acid brush to scrub the surfaces and move the acid around. Rinse quickly and thoroughly.

Phase 4: Once the acid wash has been completed, make sure the pool surface is rinsed completely – don’t take any chances here.  Acid that sits on plaster/pebble too long can “burn” or etch the surface.

Also try to prevent the acid from wearing a channel path from shallow end to deep end. This can create a worn stripe on the floor.  If this does happen, make sure it’s quickly neutralized.

If the 50/50 solution isn’t strong enough, you can increase the acid strength or the hang time (before rinsing), or scrub harder. To maximize the effectiveness of the process you can also repeat the acid wash twice using the same strength mixture.

The surface, however, should be completely hosed down before the second wash.  You don’t want to damage or “burn” the plaster.

After the acid wash, the bottom of the pool will be filled with a foamy, acid puddle. This needs to be neutralized before pumping out. A good rule of thumb is to use 2 lbs of soda ash per 1 gallon of acid used.

Broadcast the ash over the puddle while stirring with a pool brush on a pole. Use a small submersible pump with a hose to pump out the remaining acid water. Be careful where you pump it to. Even if properly neutralized, it may destroy plants, grass, animals, etc.

** You’ll end up with a puddle at the deep end of the pool – make sure this acid is neutralized and use lots of water as you’re pumping it out.  It can leave an “acid ring” on the perimeter of where the water sits.

Don’t rush the job and be safe. The fumes can be very strong, and very dangerous.

Phase 5: Let’s clean up.  Spray off before exiting the pool. If you do get acid in your eyes, rinse for 10-15 minutes – if the burning persists, consult your physician or visit the hospital.  Make sure there’s another person around when you’re completing this project.

Acid on the skin won’t usually burn too much (unless it’s over a cut or scrape), just rinse quickly, until the burning goes away.

If your pool is vinyl lined, acid is not used. Detergents, conditioners and good ‘ol elbow grease will remove the “slime”. The liner must then be “reset” with a vacuum to ensure proper fit during filling. Also, be sure not to completely drain the vinyl pool.  There can be problems getting the liner to reset properly, and there is also the possibility of the caving in (you don’t want that).

Although pool companies will vary in price for this service, some rough numbers are as follows:

  1. Drain = $125.00
  2. Acid Wash = $125-200 (depending on condition of surface)
  3. Start up chemicals = $75-150 (depending on size of pool)

Total = $325 and up.

You can do this yourself for under $125 – using the chemicals referenced above and start up chemicals (salt (if you have a salt pool), liquid chlorine, shock, conditioner).

Many may choose to hire a company to do this after seeing the process – the most important thing is to be safe and make sure it’s done properly.  If you choose to hire someone or a company, be sure to watch them so next time you can do it yourself.

:)

And that’s how you acid wash a swimming pool.

All the best,

Terry

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{ 23 comments… read them below or add one }

eddie October 3, 2010 at 1:18 pm

great discription. You helped a ton!!!
Thank You

Reply

Gordon Gatton October 31, 2010 at 8:33 am

Very informative, this helped tremendously!

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tim June 27, 2011 at 3:52 pm

Can you acid wash without draining your pool completely?

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fireyourpoolguy June 27, 2011 at 6:27 pm

Unfortunately, no Tim – for ideal results, it needs to be completely drained.

Terry

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Anonymous July 7, 2011 at 7:22 am

Thank you………very helpful. I’m looking forward to getting this project started.

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Rod July 18, 2011 at 10:19 am

Some metal pieces blew in the pool and lefts stains on my now 1 year old pebble sheen pool surface. Is it ok to just do a spot acid wash where the rust stains are? Or should I do a surrounding area so that it blends? Or are you supposed to do the entire pool no matter what? Thanks for your advice.

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Joric September 21, 2011 at 12:44 pm

Thanks a lot Terry.
You are very helpful and you are awesome!!!
Big mahalo from aloha state.

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Jim December 29, 2011 at 10:37 pm

Just had an acid wash done on our sparkle quartz pool and I think the contractor ruined the pool. The pool is normally a darker blue but it now has disgusting white splotches all over and in one area there is a spot about 4 inches wide and 7 feet long running towards the deep end of the pool. The contractor has tried adding more acid and a descaler to the pool with no improvement. He’s now blaming the company who built the pool suggesting the plaster wasn’t mixed correctly and that calcium is leaching through the gunite and staining the pool. Anyone have any suggestions?

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JAMES March 29, 2013 at 12:47 pm

THIS COST ME THOUSANDS OF DOLLARS TO FIND OUT…IF YOU WANT A PROFFESSIONAL JOB, HIRE A PROFFESSIONAL…THAT WAY, IF SOMETHING GOES WRONG, YOU CAN ALWAYS SUE THEM…WHICH, IN YOUR CASE, YOU SHOULD..

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Renee Flowers February 18, 2012 at 10:39 am

We are a group of volunteers and opening a new scheme in our community. Your web site offered us with valuable info to work on. You’ve done an impressive job and our entire community will be grateful to you.

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Joe Poole May 2, 2012 at 4:28 pm

My pool was finish this past July and the color is uneven with crazing cracks the pool company said their going to do an acid bath and everything will be fixed what do you think

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Ron Cleland May 16, 2012 at 1:08 pm

I live in Phoenix, AZ. Does the excessive heat have any bearing on when I do an acid wash on my pool?

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fireyourpoolguy June 7, 2012 at 1:53 pm

Hi Ron,

Absolutely – your window for a drain/refill here in the valley is late Oct to Mar. If it’s too warm (over about 85) it can cause cracks in your surface.

Terry

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Mike August 4, 2012 at 7:43 am

You mention a light acid wash with 3 parts acid and 1 part water, but later recommend 1 part acid to 1 part water. Isn’t the light acid wash 3 parts water to 1 part acid?

Thank you

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fireyourpoolguy August 6, 2012 at 8:39 am

Good catch Mike – it should be 3 parts acid, 1 part water.

Terry

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Johnny August 12, 2012 at 5:10 pm

Thanks for having such an informative and helpful forum. I have a 27,000 gal. quartz plastered pool in Texas that has been neglected for 2 years and needs an acid wash. Can this type of pool survive a drain and refill at temperatures above 85 degrees, or do I need to wait until winter before I get it back into shape? Right now, it is nothing more than a frog pond.

Johnny

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fireyourpoolguy August 13, 2012 at 3:13 pm

Hi Johnny – I’d definitely recommend waiting a month or more for things to cool down a bit. Try to treat as best you can by dropping some granular shock and keep circulation up so it’s not a health hazard in the meantime.

Terry

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Anonymous November 16, 2012 at 10:54 pm

Thanks Terry!
Cool weather is finally here, so I’m draining it now. I hope to start the cleaning process tomorrow.

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Fort Worth Electrician August 29, 2012 at 3:17 pm

Thanks for the instruction. headed off to get chemicals now!

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Rich September 14, 2012 at 12:23 pm

Hi Terry, Out here in the valley of the Sun also. wondering if I could use the spray canisters that we use to spray week control; around the yard or just stick wiht a flowering can.. let me know

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fireyourpoolguy September 24, 2012 at 1:58 pm

Yes, Rich – that will do the trick too.

:)

Terry

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danny September 24, 2012 at 8:28 pm

Great info! Is it ok to acid wash a pool that has plaster about 15 years old?

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fireyourpoolguy September 25, 2012 at 11:54 am

Good question Danny – really depends on the integrity of the plaster. If there’s a lot of “pits” and crevices, I would proceed with caution.

Terry

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