Will Bleach Kill Algae In A Pool?

Your pool is green and you don’t have enough money to buy algaecides. But you have each in your house, and you are now wondering if you can use household bleach in your pool.

You are not alone, I have been there before. Almost every pool owner has experienced such a thing. Even when you have the money to purchase, you may not have the time to wait for the product to arrive. So, going with the readily available product becomes a great idea.

But you want to be careful so you don’t spoil things for yourself. Well, we learn every day from our experiences. And this topic is one of the important things to learn.

Going straight to the answer, yes, you can use household bleach to kill algae in your pool. However, you need to do it the right way to get the maximum result.

There are certain things to do to get fast and better results. That takes us to the next questions.

How do I get rid of algae in my pool fast?

To get rid of algae in your pool with bleach, you need to follow the simple step-by-step instructions below:

  • Determine the pool volume:

You need to know your pool volume so you can know the right amount of bleach to add. The ideal concentration of free chlorine is in the range of 1-3 ppm. That’s about 6 quarts per 10,000 gallons of pool water.

However, for you to shock your pool properly with bleach, you need a concentration of about 5-10 p. That’s about 8 quarts of bleach per 10,000 gallons of water. You may need to add more if the algae are too much.

  • Test the pool water:

You need to test the water in your pool to determine the chemical balance. Improper balance can affect the effectiveness of the bleach.

So, test for the pH and alkalinity levels. The pH level should be between the range of 7.2 and 7.8. Anything beyond the range would alter the sanitizer effect. The alkalinity level should be 80 ppm-120 ppm. Before you can add the bleach, correct anyone that needs to be corrected.

Also, you need to check the concentration of cyanuric acid. It should be between 20 ppm and 50 ppm. To get clear pool water, you need to pay serious attention to the cyanuric acid concentration. You can correct it with a stabilizer by following the instructions on the package.

  • Vacuum and brush the pool sides and bottom.

It is important to know that algae usually sticks to the bottom and sides of the pool wall. If you add the bleach directly, it may not be able to get to the root of the algae.

To get a better result, you need to brush the pool sides and bottom with a vacuum. While vacuuming, ensure that you use the ‘Waste’ setting. If you vacuum to filter, you may end up with algae back in the pool.

But with the vacuum on ‘Waste’ setting, you don’t need to return the water to the pool. It goes down the drain. However, remember to refill the pool because the level of the water will drop.

By manually vacuuming the pool, most of the algae are filtered out of the pool, while the remaining algae are exposed completely to the bleach when it’s introduced into the pool.

  • Add the bleach (shock)

Now that your pool is ready for a shock treatment, it is important to know the right amount of shock to add. If you don’t add enough bleach, you may not get the expected result.

So, add enough bleach to about double the ideal free chlorine concentration. That is about 2 gallons of bleach or more for 10,000 gallons of pool water.


  • Don’t add the shock on sunny days or during the day. Sunlight makes the chlorine deplete faster. So, wait till evening time, when the sun must have gone down, to add the chlorine bleach.
  • Avoid entering the pool during and after adding the bleach until the level of the free chlorine has gone down to the normal level.
  • Make sure you wear protective gear to protect yourself from the chemical.
  • Test the water before using it again. If the water chemistry is not well balanced, balance it before using the pool.

How much bleach does it take to shock a pool with algae?

As we stated earlier, you need to double or triple the ideal concentration of free chlorine in your pool in order to shock it properly.

2 gallons of bleach or more will be enough to shock 10,000 gallons of pool water. That means you need over 5 gallons to shock 30,000 gallons of pool water.

Remember, these figures are for normal green algae. Some algae are tougher to get rid of. Yellow or dark green algae will require triple the amount to get rid of. You may even need more than that to shock your pool if it has black algae.

How do I get rid of algae in my pool fast?

If you follow the steps described above, you will be able to get rid of the algae quickly. But if you fail to vacuum clean the pool before adding the shock, it will take a longer time to completely clear the pool water.

So, the trick is to scrub and vacuum clean first. Furthermore, you can filter the pool after adding the shock to remove dead algae particles.

How long does it take a green pool to clear up after being treated?

The amount of time it will take to clean up your pool depends on different factors. However, your pool will clear up within 1 to 4 days of administering the shock.

It can take 2 days or more for the pool to clear up. However, you need to filter to remove dead algae. You need to consider some factors, such as pool size, level of algae invasion, type of shock treatment, amount of shock used, etc. 

How long does bleach take to kill algae in a pool?

Once the bleach comes into contact with the algae, it can take up to 15 minutes to break the algae apart, depending on the type of algae and the amount of bleach.

So, if you want to kill the algae faster, you need to add enough chlorine to have an adequate concentration to kill the algae faster.

How often should I put bleach in my pool?

If you use your bleach regularly, like more than once a week, you need to test the water up to 2-3 times every week.

Once you notice any drop in the free chlorine level, you need to add more bleach immediately. So, it depends on how often you use your pool.

Someone that uses the pool occasionally may not need to do much testing. Another factor to consider is the location of the pool.

Is there any shed from sunlight? Do you have a pool cover? All these and more play a part in determining the number of times to add a shock to your pool.

Can you mix bleach and pool shock?

Well, you can’t say it can never be done. However, it is not the right thing to do.

If the package instructions didn’t require you to do so, why would you want to try it? Playing with chemicals is not appropriate.

Moreover, you are not sure of the outcome of the mixture. The combination might even render both chemicals useless.

The best thing to do is to use one and ensure it has dissolved completely before applying the next one. So, add your shock first and allow it to dissolve before you add the next. Better still, stick to one if you aim to get rid of algae.

Is bleach the same as chlorine?

You may be wondering if there is any difference between pool chlorine and Clorox. Well, you can say that they are the same since they perform the same function.

However, they are not exactly the same chemicals. What differentiates them majorly is their concentration and strength.

Though bleach is made with the same main ingredient, calcium hypochlorite, as chlorine, they are not the same. Bleach contains about 5.3% chlorine, followed by water and salt.

On the other hand, chlorine is much stronger than bleach. It has a higher concentration of calcium hypochlorite and may contain a stabilizer, whereas bleach does not.

Is chlorine or bleach stronger?

Since pool chlorine has a higher concentration than bleach, it literally means that chlorine has a higher strength than bleach.

Pool chlorine is made with about 65% calcium hypochlorite compared to 5% bleach. So, it’s far more reactive than bleach.

Why is my pool getting green algae?

So many factors can be responsible for algae growth in a pool. The most common factors are low sanitizer level, improper filtration, poor water circulation, and out-of-balance water.

If your chlorine sanitizer level becomes low or stops functioning effectively, it will create room for contaminants like algae and bacteria to infiltrate the water.

And if your sanitizer level becomes inconsistent, check the water chemistry. Maybe the pH or alkalinity is out of balance. Even the cyanuric acid level can alter the chlorine efficiency.

Another thing is stagnant water. You don’t want your pool to settle without circulation. Stagnant water bodies help algae develop faster.

Then you need to consider your filter system. If your filtration system is not working properly, it will leave some particles, which might include algae, in the pool.

Is it safe to swim in a pool with algae?

Once algae has invaded your pool, it is no longer safe to swim in it. Many microorganisms, including disease-causing pathogens, feed on algae.

So, with the presence of algae in your pool, these microbes find their way into the pool to feed on the algae.

Moreover, having algae in the pool shows that the pool is full of contaminants that can impact your health negatively.

Can you put too much bleach in a pool?

Yes, it is possible to over shock your pool. That is why it is important to follow the instructions on the product packs.

Even with the instructions above, you will not add excess bleach to your pool. Having an excessive amount of chlorine in your pool is not good for your health.

It can lead to health complications, especially for those with health conditions like asthma and other respiratory diseases. So, avoid using your pool if there is too much bleach in it.

More so, it can be detrimental to your pool components. Excess chlorine in the pool can react with the components if exposed for a very long time.

However, there is no cause for alarm if you notice this. But make sure no one uses the pool until the free chlorine level drops to the normal level of 1-3 ppm, or below 5 ppm.

To help it drop faster, expose the pool water to sunlight.

Should I drain my pool to get rid of algae?

Yes, you can drain your pool to get rid of algae. But you have to do it properly. Scrub the pool bottom and sides before draining to enable you to remove the algae.

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