How to clean a green pool with bleach

How to clean a green pool with bleach

One of the most common problems that come with having a pool is that you have to deal with the pool turning green with time, especially during the summer. This green coloration is, in fact, due to Algae, which are microscopic organisms that thrive in an aquatic environment. Swimming in this kind of water can not only cause Algae to stick to one’s body, making the skin surface slimy, it can also cause health complications.

In this piece, we will take you through simple, easy to understand techniques using bleach that would aid in dealing with green pools effectively.

The first thing to know is the reason for the green pool water in the first place:

Causes of Green pool water

Unbalanced pH

The most likely reason for green pool water would be the unbalanced pH of the pool, which is usually due to little or no chlorine present, other chemicals such as ammonia that is released in the pool by people swimming, which would promote Algae bloom.


A warm, humid temperature would favor Algae growth over a cold one, which is why green pool water is more common in the summer.

Debris and Dirt

Debris such as wrappers and cans can get to your pool over time; they usually float on the pool’s surface and can cause a green pool. Using a net to skim or sweep them off the surface is a great way to take care of this.

Pollen: Pollen from nearby plants, trees, and flowers can be carried by the wind and get into your pool, and even if you have a filter system, it might not be of much help since the pollen is relatively small for the filter to remove, however pollen is relatively harmless. Skimmer baskets can help in removing pollen from the pool adding a flocculant also helps.

Damaged filtration system

If the pool filtration system is faulty, the water would undoubtedly get dirtier with time as debris and other items would acclimate in the pool, and there would also be a chemical imbalance.


Metals such as copper from heating systems in pools and cleaning agents can cause a green pool. When you introduce chlorine in a pool with excess metal, the metals will oxidize, and in the process, the pool water would turn green with time; it can even affect the walls and paint of the pool. To fix the issue of excess metal in your pool, you can check the filtration system to see whether the metal components are rusting. You could also use sequestrants to make the metals coagulate or come together as they are easily removed way.

Will bleach clear a green pool?

For bleach to effectively clear off the green in your pool you will need to follow a number of steps, these steps have to be followed effectively to ensure complete removal. These steps include:

How to clean a green pool with bleach

Clean the surroundings of the pool

Cleaning the vicinity of the pool is paramount before attempting to clean the pool itself, such as the walls, edges, and ladders. You could also clean the built-in pump filter; a very small amount of bleach and a good scrub is often sufficient to do this.

Inspect the pH level

Before you attempt cleaning a green pool with bleach, the first thing is to check the pool’s pH, which is an important factor as you wouldn’t want to add too little or too much chlorine into your pool.

To check the pH levels and other chemical content effectively, you should use a high-quality pool testing kit with a DPD chlorine test.

The optimum pH level is usually about 7.2 to 7.8; if the pool’s pH is lower than that, you could add some sodium bicarbonate; if it’s higher than 7.8, adding muriatic acid would lower the pH.

Cleaning pool walls with bleach

When adding bleach into a pool, it is essential to note the stabilizer (Cyanuric Acid) in the pool. This acid helps to prevent chlorine from being decomposed by the sun’s ultraviolet rays. It is important for this stabilizer not to be too small nor too much (As it can inhibit the action of chlorine).

It is important to note that the stabilizer (cyanuric acid) does not evaporate with time like chlorine; hence it accumulates in the pool; the only way to get rid of the stabilizer is to empty the pool bring in freshwater.

Adding the bleach (“Shocking” the pool)

The next step is adding your bleach into the pool, which is also termed “shocking” your pool, after taking the measurement of the pool and calculating the amount of chlorine needed.

A simple hint in knowing the right amount of bleach to add is that one-half-two gallons of bleach per 10,000 gallons of water will raise the chlorine levels by 5ppm; using this clue, you should be able to calculate the amount of bleach to add.

The main point of adding the bleach is to find a way to introduce chlorine into the pool since it is an effective antibacterial agent and would kill the Algae. The preferable bleach would be liquid bleach which contains a salt Sodium Hypochlorite.

In addition to water would release a chlorine ion that would immediately attack the Algae and disinfect your pool.

How long after a bleach can you swim

If you have tried the methods above, you should be able to see results within 24 hours. However, if there is no change and the pool is so green you can’t see your hand when you dip inside it, it would be better to empty it.

When you do this, it is also advisable you clean the pool walls and floor with bleach thoroughly to remove all the residual dirt and microbes;

Here are some easy steps in cleaning pool walls and floors.

  • Please turn off the pool filter, sandpaper filter, and heater first to avoid any damage done to them.
  • Prepare the amount of bleach to be used.
  • Apply the bleach, and you could then wait for some minutes.
  • After waiting for some minutes, you can now scrub the areas thoroughly and rinse.
  • Refill the pool.

Once you have effectively cleaned your pool, the next step is to maintain it properly. Here are some simple maintenance tips to keep your pool clean and sparkling.

Also read: Algae keeps coming back in pool

Bleach in swimming pool to kill algae

Maintenance Tips

  • Adding chlorine regularly

It has already been established that the most common cause for green pool water is Algae, a microbe that thrives when the chlorine levels are low, so keeping the chlorine levels sufficient is important at all times, even after you have cleaned the pool. Adding chlorine to a pool depends on a number of factors such as pool size, how often you use the pool, how many plants, shrubs, and trees are present around the pool. How much sunshine gets to the pool since the sun’s UV rays decompose the chlorine present.

  • Cleaning the pool vicinity

Cleaning and clearing the pool surroundings helps reduce the amount of debris that can enter the pool; doing this once or twice a week is satisfactory.

  • Covering the pool surface

Since sunlight reduces the chlorine content in the pool, you could cover the pool surface with an opaque material when you are not utilizing it to block the sun’s UV rays.

  • Cleaning the filter system

Your pool’s filter system is responsible for removing pieces of dirt in the pool; over time, it can be clogged with excess dirt and be blocked, impairing its function. Therefore, to maintain the pool, removing and cleaning the filter system regularly is essential.

  • Cleaning the heating system:

Over time the metallic components of your heating system may start to get rusted, introducing metal into the pool, which affects the chemical balance. Chemically cleaning the heating system every now and then helps to keep the chlorine and pH content in check.

  • Testing your water

Testing your water regularly for certain factors is important, and this would help you to prevent a lot of issues arising from the pool. Testing for chlorine content, pH and alkalinity levels, metallic content, and cyanuric acid content is a must-do. You could do all this with a standard pool testing kit or take a portion of the pool water and get it tested at a water testing centre.

  • Replacing the water

Even though you properly maintain your pool and clean it all year round, replacing the water is still necessary. Not only does this check the stabilizer levels, but it also always helps you to clean the walls and floors of the pool properly. Most public pools replace the water of their swimming pool three to four times a year.


A green pool is truly an unpleasant thing; not only is it visually revolting, but it can also cause health issues and stain the wears people use. Although the three common causes of Green pool water are Algae, Metal, and Pollen, we have given ways to resolve any issue each of them might cause. It is also advisable that after you finish adding chlorine or shocking your pool.

You should leave it for 24 hours before using it, and shocking the pool can be around late afternoon or evening period since the sun’s UV rays decompose chlorine. Cleaning and maintaining a pool is usually straightforward and not too much work, but finding and hiring pool cleaning services is a good choice if you feel it’s too much for you.

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