How to Clean a Green Pool

Last updated on November 30, 2022

Has your pool water gone green? Here’s a step by step process of how to clean a green pool as fast as possible. Read on!

As a pool owner, you’ve probably witnessed your pool turn from sparkling blue to green. Generally, your pool will become green due to the growth of algae which progresses if not addressed. However, the causes of overgrowth tend to vary.

To help you tackle this problem, we’ve outlined 5 very easy ways how to clean a green pool, so you don’t have to ever see a green, slimy, and algae-infested swimming area ever again in your home.

Why Has My Pool Turned Green?

green pool

As mentioned above, the reason why your pool turns green is due to algae growth. However, the overgrowth is normally perpetrated by several other factors. The common reasons include improper pH balance, clogged filters, and changes in weather.

How to Clean a Green Pool

green pool

Below are the 5 common ways to clean a green pool.

Lower Your pH Level

As mentioned above, the reason why your pool may facilitate the growth of algae is due to imbalanced pH levels. A low pH level erodes the pool environment and causes eye irritation whilst a high pH level will not kill bacteria or algae yet, cause skin irritation. Furthermore, an imbalanced pH level can lead to water discoloration.

First, test your water pH level to test if it needs to be balanced or not. You can invest in versatile pool strips that allow you to test the chlorine, bromine, hardness, alkalinity, pH, and cyanuric acid levels of your pool water. Simply dip the strip into the pool water, wait for a few seconds, and compare the readings to the strip’s value table.

For one, green pool water already indicates that the chlorine levels are low – so you don’t need to check that. For a healthy pool, the pH should be around 7.5. To balance this pH, simply use a chemical known as sodium bisulfate. The amount you add depends on the pH value you get. The sodium bisulfate normally comes with instructions on how to add it and how much to add.

Kill the Bacteria and Algae

Alternatively, after testing your pool’s chemical level, you can simply shock it. Shocking incorporates pouring super shock liquid or granular chlorine, such as calcium hypochlorite, to instantly kill bacteria and algae in the pool water. Depending on the chemical levels of the pool water, the shocking material included instructions will guide you on how much to add.

Pump and Filter the Pool Water

Another reason why your pool may be green is due to being unfiltered for a long or the filter not working. If it’s the latter, you may have to remove the filter and clean it or replace it with a new one. After that, you want to pump the pool water and filter it to regain balance. To do so follow these pool maintenance steps:

  • Shut off the pump, bring out the backwash hose and check the waistline for any closed valves.
  • Turn the multiport valve handle to backwash.
  • Turn on the pool pump to allow water to flow out the backwash hose.
  • Continue to backwash until clean water runs through, then, shut off the pump.
  • Turn the valve back to filter and begin to filter the water. Increase the pressure for faster results.

Before, you pump and filter the pool, you can floc it as well. Floccing your pool simply means adding a flocculent to the water. Flocculants help to clump the pool debris together. This means that heavier debris and algae fall to the bottom of the pool.

You may still notice that your pool water is green but less dense. This is because the more microscopic algae and debris will remain at the top. This allows you to filter the water with more precision whilst the debris at the bottom can easily be picked up through vacuuming.

For even more precise results, you can add algaecide to the water to kill the algae. Similar to when you use flocculants, the algaecide will kill the algae and force it to fall to the bottom of the pool.

Vacuum Pool and Brush the Surfaces

Sometimes the solution to clean a green pool may simply be to vacuum the pool and brush the walls and floor. When you begin to clean a green pool and ridding it of bacteria and algae, the first step is to vacuum the pool to waste.

Set the valve on the vacuum filter to waste and let it remove as many algae and debris from the bottom of the pool. Then, brush the pool walls, steps, and floor. You can choose to either use a regular pool brush or an algae one.  For removing stubborn algae, a heavy-duty algae brush works better than the regular soft nylon bristle ones.

Drain Your Pool

Sometimes, your pool water may reach a point where the only antidote is to drain the water. If you notice that your pool has turned dark green or bordering blackish green, you definitely have to drain your pool.

As a general rule of thumb, if you cannot see at least six to eight inches below the surface of the pool water, then, the water needs to be drained. After draining the pool, acid wash the surface to ensure that you completely remove and kill off all the algae.

Bottom Line

Even after you clean a green pool, you want to ensure it never turns green again. Thus, the best practices to ensure your pool never turn green include consistently checking your filters and pumps. Remember, algae survive best in stagnant waters. Thus, if your pump and filer don’t work to the adequate capacity, you most definitely will have an environment to which algae thrive.

Furthermore, ensure that you at least brush and vacuum your pool weekly. Scrub the surface, floors, and walls as well as vacuum the bottom to ensure no algae or bacteria are growing. Additionally, test your pool’s pH and chlorine levels at least twice a week to ensure they are balanced. Your chlorine and pH levels should be at least 7.6 and 7.4, respectively.

Lastly, when your pool is not in use, make it a point to cover it to prevent debris and other microorganisms from falling into it.


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