How to Acid Wash a Swimming Pool

Last Updated: January 29, 2020 Approved

Whether your pool looks like a swamp, or you just want a fresh, clean-looking appearance, acid-washing your swimming pool can help. Also called "drain and clean," pools need this type of cleaning when winterizing the pool isn't done correctly, or algae has taken over due to the pool not being used or maintained in a while. The acid-wash process essentially strips the top layer of plaster to reveal fresh plaster beneath, so it's not recommended to do it often. But once in a while is a great idea!

Steps

1
Drain your pool completely. As you drain, make sure to clean up any debris as you go. If your pool has an autofill, you should make sure that you turn it off during the drain. Once your pool is completely empty, start the acid-wash process.^{[1]
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2
Change into protective gear that includes clothing, goggles, mask, gloves and boots.^{[2]
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3
Mix 1 gallon (3.8 liters) of acid with 1 gallon (3.8 liters) of water in a watering can. Acid must be added to the water and not the other way around.^{[3]
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4
Wet down one of the walls with the hose. The hose should not have a nozzle and water should be running from the hose at all times.^{[4]
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5
Pour the acid mixture on the wall from top to bottom in 10-foot (300 cm) sections at a time, leaving the acid on the plaster for about 30 seconds. During this time, you should be scrubbing the wall with a brush.
6
Rinse the section you just acid-washed quickly and thoroughly.^{[5]
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Research source} Before moving to the next section, make sure you rinse the wall well so the acid doesn't continue to eat the plaster.
7
Neutralize the pool after the acid-wash is complete. The acid-washing process leaves a foamy puddle of residue on the bottom of the pool that must be removed before it damages the plaster.
- Apply soda ash to the acid puddle, scrubbing the mixture with a pool brush. You will need to use 2 lb. (.9 kg) of soda ash per 1 gallon (3.8 liters) of acid.
- Pump the mixture into a bowl using a submersible pump.
- Dispose of what you pumped, as the acid can kill frogs, fish and plants. Rinse out the bowl.
- Pour water over any remaining residue, rinsing carefully around the drain.

Community Q&A

Question

I poured acid before disposing the water in the pool. What must I do now?

Uthra Balakrishna

Community Answer

Quickly drain it off. The acid will be stuck on the walls. Clean it and pour the water.
Question

For how long I should wait to enter the pool after I put acid?

Community Answer

Depending on how much acid you added and if your filter is moving the water rapidly about a hour, check with your test kit (phenol red), it will let you know the acid level. I add a bit less than calculated and then adjust further in small doses, that saves money. Note: you should retest next day as some cement/concrete pools react with acid causing a small pH bounce.
Question

How can you tell if the acid is working?

Community Answer

If the dirt disappears, it's working.

Warnings

Work carefully around the acid. Wear protective clothing, transport the acid safely by securing it in the vehicle, rinse off after you've finished acid-washing the pool, and have at least one other person working with you.

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If the acid is not rinsed completely, it will continue to etch the plaster. Be careful not to allow the acid to run from the shallow end to the deep end as it will create an etched path on the pool floor.

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The acid-washing technique should never be used on a vinyl-lined pool. Detergents and conditioners work best for this type of pool.

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