How to Acid Wash a Swimming Pool

Co-authored by Rob Litman

Last Updated: February 20, 2024 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!

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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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Acid must be added to the water and not the other way around.
The hose should not have a nozzle and water should be running from the hose at all times.^{[3]
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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.
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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.
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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.

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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.

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

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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.

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How can you tell if the acid is working?

Community Answer

If the dirt disappears, it's working.

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Tips

If you do not see results after the first attempt, you might need to increase the acid/water ratio, scrub harder or increase the time the acid is on the wall. You may have to repeat the process a couple of times to get the walls clean.

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Professionals will add a cleaning additive, like Bio-Dex White & Bright or Aquapoxy Etching Cleaner. This will thicken the acid mix making it adhere better to the walls of the pool. It will also neutralize the smell of the muriatic acid and reduce etching cause by muriatic acid.

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If acid gets into the eyes or mouth, flush the area with the hose (no nozzle) for 15 minutes. If contact is made with the skin, rinse for 30 seconds as soon as contact is made.
- If possible, dissolve some baking soda in the water to be washed to help neutralize the spilled acid.
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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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If you accidentally used too much acid, rinse off the excess with water in which you have dissolved a little calcium carbonate, baking soda, or hydrated lime to neutralize it.

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