Essential pool maintenance: How to acid wash a pool

Having a backyard in-ground pool is definitely a luxury. As with all things expensive, it calls for a certain amount of care and maintenance. However, sometimes, using a test kit, adding chemicals, or even scrubbing and vacuuming the pool just doesn’t cut it. You may need to acid wash your pool.

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What is an acid wash?

If you’ve ever been to a dermatologist to get your face exfoliated, you will know that a mild acid is applied on your face to remove a thin top layer, allowing younger, fresh skin to emerge.

Acid washing your pool is similar, except that the acid used isn’t really mild. In fact, you would be right in exercising extra caution whenever you use acid to clean your pool.

Acid washing your pool does more than cleaning it. It peels away a thin layer of plaster, taking with it dirt and stains left by minerals, algae, and the elements. Once you’re done, what you will be left behind with is a clean and stain-free layer of plaster.

Keep in mind though, that not all kinds of pools can be acid washed. Only in-ground concrete plaster pools and gunite pools can withstand it. Try acid washing a vinyl pool or an above-ground one and you will need to replace the entire pool wall liner!

When is a pool acid wash necessary?

Stains and discoloration

Sometimes, you may find discoloration and stubborn stains that have developed over time in your pool that do not go no matter how hard you try cleaning them up. Chlorine, first and minerals are often the culprits.

For example, a black plaster pool may start getting a grey tinge because of excess calcium. Magnesium and copper both can turn white plaster blue. 

Algae

Stubborn algae spores can also be difficult to scrub out, causing discoloration to pool surfaces. If you keep seeing repeated algae blooms even though you clean your pool regularly, it’s a sign that you may be able to clean out the spores successfully. 

Another reason for staining caused by algae could be because your pool was not properly winterized, or because it has been stagnant over a long period of time. Acid washing your pool against algae is a last resort when all else fails.

Repairs

Sometimes, you may be replastering only a portion of the pool and may need to acid wash it before adding the new layer of plaster. This will make sure you have no algae spores remaining underneath the surface.

Age

As your pool gets older, discoloration may happen simply because of years of exposure to the sun and due to the chemicals used to clean the pool. Once again, an acid wash is just what the doctor ordered.

How often should your pool be acid washed?

Acid washing your swimming pool is not something you want to do very often, because even if you do it once a year, you will wear your plaster out entirely. Ideally, unless you have a severe algae bloom, acid wash your pool once every five years.

How to acid wash your swimming pool

Materials

Here’s a list of what materials and tools you will need to acid wash your pool.

1. A garden hose
2. A garden watering can
3. Submersible pump
4. Discharge hose
5. Around 20 gallons of acid
6. Protective goggles
7. Gloves
8. Boots
9. A mask
10. Soda ash
11. A screwdriver
12. A chisel
13. A pair of pliers

The washing process

Here’s a step-by-step description of how to go about the acid wash.

Draining your pool

It isn’t without reason that this method of pool cleaning is called the drain and clean method. Drain your pool water out completely and once that is done, thoroughly clear out any debris left behind in it. If your pool has an auto-fill function, be sure to turn it off.

Protect yourself

Working with acid is hazardous, so make sure you protect yourself with adequate clothing, boots, protective gloves, goggles, and a mask.

Mix the acid

The acid you will use is muriatic acid, which is a powerful, corrosive mineral acid. Be extra cautious while handling it.

Combine 3.8 liters or 1 gallon of acid with 1 gallon of water in the garden watering can. Keep in mind, that water should be added to the can first and then the acid, never the other way around.

Wet a wall

Using a hose without a nozzle, saturate one of the pool walls. Make sure there is an uninterrupted supply of water through the hose.

Start the acid washing

Pour the acid and water mixture over the wall from the top to the bottom, working in ten-foot sections at a time. Let it sit for around 25 to 30 seconds, and then scrub it vigorously using a pool brush.

Wash it off

As soon as you are done scrubbing a portion of the wall, wash it off immediately using the hose. The longer the acid is allowed to remain, the more plaster it will eat into.

Repeat this process until the whole pool has been cleaned.

Neutralize it

Acid washing will leave a bubbly pool of residue once you are done. This will have to be removed immediately before it continues to eat up more plaster.  Soda ash, normally used to increase the pool’s ph level, is used to neutralize the acid.

Apply 2 lb. of soda ash per 1 gallon of acid used, and start scrubbing the puddle with a pool brush. Then, use a submersible pump to remove the mixture into a bucket. 

Be sure to safely dispose of this waste, because it is harmful to both plants and animals. Any leftover residue should be washed away into the pool drain.

Costs

How much acid you will need will depend on the size of your pool, but on average, the cost of acid washing a pool is between $0.06 and $0.51 a square foot. This works out to between $178 to $255 for an average-sized pool.

Written by Narayan Shrouthy. July 21, 2022

Narayan is a content writer for Kukun. With experience in both content writing and editing, Narayan mixes his writing and love for reading with his passion for music. As an active musician, He aims to be a key player in Kukun's content experience.