How to Acid Wash a Pool

Is your pool retaining algae? Are there seemingly permanent stains on the surfaces of your pool? There are many ways to clean algae and dirt in a swimming pool. But there may come a time where no methods are working, and you will need to drain the pool and acid wash. Acid washing can help restore your pool’s natural beauty and kill any stubborn bacteria or algae.

In this article, I’ll detail the reasons why you may want to acid wash your pool, as well as some safety precautions you need to take. I’ll also reveal my step-by-step guide for acid washing your swimming pool. Make sure you don’t skip reading the safety precautions first, though!

When is it Time to Acid Wash Your Pool?

If you can never get the water or surfaces up to par, even after keeping up your cleaning schedule, it may be time to acid wash the pool.

If you are consistent with your pool maintenance, you shouldn’t have to acid wash your pool often. Every 5-7 years is the usual benchmark. I do not recommend acid washing more often than this because the harsh muriatic acid can damage the pool’s surfaces when overused. Some signals that your pool may need an acid wash are:

  • Stains
  • Faded plaster
  • Stubborn algae growth

You may also consider acid washing your pool if the water has been stagnant for some time. Algae and dirt can settle into the pool walls if the water is not flowing, which can be very difficult to clean properly. You can try many different solutions to get it looking good again, but you need to know when to drain your pool and give it a good scrub.

Returning your pool to pristine condition does require a little bit of work, but the results are worthwhile. An effective acid wash and cleaning can help keep your backyard looking irresistible.

Lastly, the type of swimming pool you own is significant. Concrete and gunite are the only two materials that can safely withstand an acid wash.

Safety Precautions

Before you begin an acid wash, make sure you’ve taken the proper safety precautions. Muriatic acid is caustic and only slightly less corrosive than hydrochloric acid, so it can quickly eat through your clothes and irritate your skin and eyes.

Wear acid-resistant gloves: Protecting your skin is paramount when handling muriatic acid. Standard rubber gloves will not do, so make sure to buy heavy-duty, latex-resistant gloves.

Wear a mask that blocks fumes: Since muriatic acid can give off dangerous fumes, you’ll need to wear a respirator mask designed to block noxious fumes.

Wear appropriate clothing: When handling acid, it is unacceptable to wear open-toed shoes, shorts, or a t-shirt. I recommend wearing full-cover clothing that you don’t mind getting damaged.

Wear eye protection: Your eyes are even more sensitive to acid than your skin. You can even lose your eyesight if acid splashes in your face. So, make sure to wear proper eye protection.

Keep the surfaces wet: When scrubbing your pool with the acid solution, keep surfaces constantly wet with clean freshwater. Also, be sure to keep the solution moving toward the drain at all times. Otherwise, you may develop dips and dents on the surface of your pool.

Always add acid to water: Adding water to the acid can create a chemical reaction that will cause the acid to bubble and splash. So make sure to fill a bucket with water before adding the acid to dilute.

In addition to a handful of safety supplies, you need the tools and equipment necessary to get the acid wash job done. If you don’t own a drainage pump, several garden hoses, or a specialized scrub brush, you’ll likely need to make a quick shopping trip.

Supplies Checklist

Before you acid wash your pool, you’ll need to have:

  • Muriatic acid
  • Safe clothing, glasses, gloves, and boots
  • A powerful submersible water pump
  • A long drainage hose
  • An extended garden hose
  • Washing soda
  • Water testing kit
  • Algae brush
  • Acid brush
  • High-pressure spray nozzle

You should also ensure that you have access to clean running water and a sewer. If your garden hose cannot extend from your water source to your pool, purchase a longer one or an extension hose. Check your drainage hose to ensure it can reach the nearest sewer opening.

Finally, double-check the durability of your safety apparel. If it’s not acid-resistant, I recommend investing in equipment that can handle contact with corrosive chemicals.

Okay, now let’s get to the steps for washing.

How to Acid Wash a Pool: Step-By-Step

Once you’ve gathered your supplies, it’s time to get started. Ensure that your safety gear is properly secured and positioned, taking special care to protect your skin, lungs, and eyes.

Here is the step-by-step breakdown for acid washing:

  1. Drain the pool completely
  2. Scrub surfaces
  3. Prepare the acid solution
  4. Scrub and rinse pool surfaces
  5. Make the wastewater safe
  6. Drain and refill
  7. Balance chemical levels

By following these seven essential steps, your pool’s acid wash goes swimmingly. You’ll also keep groundwater safe while restoring the look and condition of your pool.

While you could choose to tackle this project alone, it may be wise to consult with a professional when draining an inground backyard pool. Hiring a pool maintenance crew to acid wash your pool could help you save money on equipment, ensure that the cleaning goes smoothly, and prevent costly or painful accidents.

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Step 1: Drain the Pool

Attach the drainage hose to your submersible pump and drag it to the closest sewer grate or opening. Then, turn the pump on and lower into the deepest area of your swimming pool. Depending on the size of your pool and the power of your pump, it may take several hours to drain your pool entirely.

Avoid starting this process if there is heavy rain. The differential pressure between the groundwater and the pool water could cause an inground pool to rise up when drained. I wouldn’t recommend acid washing during a scorching hot day either, since high heat can damage the plaster.

Step 2: Scrub the Surfaces

Once you’ve successfully drained the pool, remove debris from the bottom of the pool. You can get a jump start on stain removal using an algae brush to remove surface contaminants. Keep surfaces wet by running small amounts of fresh water into the pool. But you don’t want water puddled at the bottom.

You could also use a spray bottle or watering can instead of a hose. But a garden hose is a much more effective method for such a large surface area.

Step 3: Prepare the Acid Solution

Follow the manufacturer’s instructions when mixing your acid solution. Always use clean water as your solution base and slowly add muriatic acid. Attempting to add water to the acid could result in chemical boiling, a potential hazardous reaction.

If you feel confident about your chemistry skills, you can go ahead and create your solution. Use a resin container to hold your mixture. Other materials may instantly weaken after coming into contact with muriatic acid. A leaky container is dangerous, even if you’re wearing protective gear.

Step 4: Scrub and Rinse Surfaces

Keeping your pool’s surfaces wet, go ahead and begin applying the acid solution. Use your acid brush to scrub away stains after waiting for about one minute since applying the acid mixture. Keep clean water running on these stains while you scrub. It will most likely take some time, but you should take this opportunity to scrub all of the surfaces of your pool with the acid solution. A thorough job will get the best results and prolong the beauty of your pool.

When you finish scrubbing, go ahead and give all of your surfaces a thorough rinse. Always rinse toward the drain, allowing the wastewater to flow toward the lowest part of your pool.

Step 5: Make the Wastewater Safe

Before you drain the acid-water solution into the sewer, ensure it’s safe. Pouring the acid wash solution into local sewage systems is incredibly dangerous.

Not only could the solution eat through your drainage hose or pump, but it could also cause significant harm to the environment. Adding soda ash as you rinse will neutralize the acid and prevent any unwanted corrosion. It will also keep your community free of any waterborne pollutants.

For every gallon of acid, be prepared to sprinkle in two pounds of powdery washing soda ash. This ratio should result in a fairly neutral blend.

Step 6: Drain and Refill

After confirming that the remaining wastewater is neutral and safe to dispose of, restart your drainage pumps and hoses. I recommend running clean water into the pool while draining the wastewater. Doing so can help you remove all traces of the acid before refilling the pool.

When you’re confident that all the dirtied, acidic wastewater has been rinsed from your pool surfaces, shut off your drainage pump and remove the hose from the pool. Then use the garden hose to refill the pool.

As with draining, refilling could take quite a while. Using multiple hoses or water sources could help reduce the amount of time it takes to refill your pool.

Step 7: Balance the Chemical Levels

Once you fill the swimming pool, add sanitizing chemicals to your pool to balance the pH and chlorine levels.

Replace any pumps or valves, and lastly, enjoy your gorgeous, glimmering swimming pool!

Frequently Asked Questions

How Often Should You Acid Wash Your Pool?

I recommend a minimum of 5 years in between acid washes. Of course, there will be times that you are in desperate need of one earlier. But it is not good for the pool’s surfaces in the long run.

What Kind of Pool Should Be Acid Washed?

You should never acid wash a vinyl or an above-ground pool. The acid will eat away at the lining and can cause holes and leaks. Only use acid to wash inground concrete or gunite pools.

What Are the Risks of Acid Washing Pools?

The risks of acid washing include injuries to yourself and damage to the pool. Improper handling of the acid can lead to chemical burns on the skin, eye damage, and respiratory issues. If the acid sits on your pool’s surface too long, it can discolor or even damage it.

How Much Does It Cost to Acid Wash Your Pool?

Another reason that acid washing should only be done when necessary is the high price tag. Draining and refilling your pool and purchasing all of the necessary equipment can be very costly. The national water cost average is $9 per 1000 gallons. This average does not include the cost of equipment and muriatic acid.

Final Thoughts

Acid washing your pool will refresh the beauty of your pool. It may be hard work and time-consuming, but the benefits make the effort worth it.

Don’t hesitate to call a professional if the task seems too daunting. There is no shame in wanting it done safely and correctly.

No matter which route you decide to take (DIY or getting some help from a pool maintenance crew), you’re bound to enjoy the results of a high-quality, stain-removing acid wash.

Questions about the process? Shoot me a note, I’ll be happy to help.

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