Just Filled Pool and Water Is Green

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Many people complain that they just filled the pool and the water is green. Well, there could be multiple reasons behind it. But do not worry. It is all about having the right knowledge about what actually is causing this problem. The solution becomes obvious, and simple as soon as you identify eh issue.

In this article, we will learn the reasons behind why the pool’s water gets green. Also, we will go through steps about how to clean the pool when the water inside it turns green due to algal growth. Go through all the steps, and follow them to get your clean pool back.

Steps to Getting Rid of Green Water in Pool

Test the Pool’s Water

Start by checking the chlorine level in the pool’s water. You will require a chemical test kit for this purpose. Along with chlorine, also determine the pH of the water. This will help you understand the exact extent of the problem in the pool’s water.

We know the fact that when the chlorine level in the water drops below 1 ppm, the water turns green. In such a case, you have to add chemicals to the water. They shock the water and increase the chlorine level. As a result, the algae grown inside will die.


  • Proper maintenance should be done regularly.
  • Make sure the water filters are always working.

Without taking care of these two things, you cannot stop algae from growing again. It will take only a few days to go back to that ugly situation. So, keep an eye on filters and maintenance even if it is your new pool start-up.

Balance the Poll’s Water pH

Before you fill the pool with water, make sure you balance the chemistry of bases and acids inside it. This means you have to maintain a certain pH of water which normally is 7.8. This is at the high end of the pH; therefore, the algae will not be able to grow in such water.


  • As soon as you add water to the pool, turn on the pump. It will help the chemicals circulate in water and develop a uniform pH.
  • After checking pH level, add sodium bicarbonate to increase it and sodium bisulfate to decrease its level.

Check the Filters

As pools are often made in open spaces, it’s common that the tree leaves, sticks, and other debris clog the water filters. You should try backwashing these water filters. Try to do it before adding the chemicals so that they could reach the filter mesh easily. This is how it can kill all the algae present inside the pool.


  • Keep running the water filter for one day at least after filling above ground pool with water for the first time. This practice is important because it will help in flushing out all the residues of algae from the pool water.

Scrub the Pool Walls

You should scrub the walls of the pool with the pool brush. This should be done thoroughly so that the algae that are stuck to the walls come off. Now you can add fresh water and chemicals. They will work perfectly on every corner of the pool’s surface.


  • Break the areas where algal buildup is tough. It will help the chemicals work faster and easier.
  • Always use a nylon scrubbing brush for pools with a vinyl surface. Scrubs with wires can damage such surfaces.

Shock the Pool

When you just filled the pool and the water is green, you need to immediately shock the pool. This could be done with 70 percent chlorine solution. It has the ability to handle the bacteria as well as algae that are causing the dirty green color.


  • Always use the right amount of water that is suitable for the amount of chlorine you are adding.
  • If the problem is of a great extent, treat the pool with chlorine solution multiple times.
  • The water should look cloudy as you add the chlorine solution. Run the filters to turn it clear.

Use an Algaecide

When you find out that the chlorine level in the pool’s water is below 5.0, you should add an algaecide to it. Let this treatment work for at least 1 day inside the pool. This will help in the thorough cleaning of any residues of algae that might still be present inside it.


  • You can use any brand of algaecide as they are all very effective.
  • Always follow the instructions, and learn how to put chemicals in the pool for the first time. Do not overload the pool with this chemical because that would ruin the quality of water.

Prevent Pressure Buildup

Another step that you should follow includes the prevention of pressure buildup in the filters of the pool. This is crucial not only when you do it for a fairly used pool, but also when you are filing a new pool with water.

You can do this by cleaning the filters regularly so that even the dead algae go off the mesh. It will come out of the mesh and fall on the base of the pool structure. It will lose its green color with time, so do not worry about it and let it stay there.

Vacuum Dead Algae

Once more you need to brush all the sides of the pool. If you see there are a lot of algal residues inside the pool, you may use a flocculant. This will help in binding the algal dead particles together. You can then vacuum them easily.

You can leave them inside the pool as they are harmless. However, it is better if you have the vacuum, then make use of it. It is always better to remove them, however, leaving them inside does no harm as per the reports.

Run the Filters

You should run the water filters of pools for a long time until all algae are gone. Even after this step, sometimes you will see the algae is coming back. IN this case, you should repeat the shock treatment and scrub once again. Keep doing it until the water is clean and free from algae.

Recheck Chemicals

This is not needed when you know how much chlorine to add to the pool the first time. However, it is recommended that you check the level by using the chemical testing kit. Adjust the levels as per requirement.


We are sure that the above steps are very practical and helpful for those who are struggling with algal growth in their pools. No matter your pool has had standing water for many days, or you just filled the pool and the water is green.

The above-mentioned guidelines will allow you to get rid of algae and green color in the first case as effectively as in the latter case. It is always better to educate yourself about how to treat pool water for the first time before you build it for yourself. You will be able to prevent this problem, and would never feel a need to do the hard task of removing it.

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