How to Clean a Green Pool?

Learning how to clean a green pool is indispensable, especially during warmer months when it can turn green overnight! Beyond destroying the appearance, a green pool breeds bacteria and other harmful organisms. Worry not, because this blog will take you through the steps of turning that green pool into a clean, safe, and sparkling pool.
In this article:
- What Is a Green Pool?
- How to Clear Green Pool Water Fast
- Causes of a Green Pool
- Types of Algae That Can Cause a Green Pool
- Best Practices to Avoid a Green Pool
What Is a Green Pool?
A green pool is a pool that has assumed a greenish color due to algae growth. Pool algae are fast-growing and thrive well in imbalanced water, especially when chlorine levels are low, or the water's pH is out of range. However, other factors such as poor filtration, favorable weather conditions for algae growth, and debris buildup also bring about algae blooms.
How to Clear Green Pool Water Fast
It's a tricky thing, but trust me, it's really not that difficult to turn your greenish pool water back to clear- and not even once do you need to drain your pool water! If you wonder how to fix a green pool, here’s what you’ll need.
Tools and Materials for Clean Your Green Pool
Gather these before you start working:
- Pool testing kit
- Pool shock (calcium hypochlorite or liquid chlorine)
- Pool brush
- Manual or automatic pool vacuum
- Algaecide (optional)
- Clarifier (if water is cloudy)

Step 1: Test the Water Chemistry
Use a pool testing kit to test the pH, chlorine, and alkalinity of your water. Ensure the pH level is between 7.2 and 7.4. Adjust your chemical levels, then continue the process.
Step 2: Shock the Pool
To get rid of the algae, the pool must be shocked with chlorine. Use the recommended dosage according to the volume of water in your pool. To maintain the efficiency of the shock treatment, do it at dusk or late to prevent it from being degraded by sunlight during the day. Give it at least one night to fully appreciate the effects of a shock treatment.
Step 3: Brush the Inside of the Swimming Pool
Gently brush the edges of the pool to clean up the residual waste on the walls, floors and steps. Work especially on the spots where the most intense algae growth is present. This assists in loosening the build-up so that the chemicals and filter can work effectively.
Step 4: Filter the Water
After shocking and brushing, the pool pump should be used continuously to remove any remaining dirt, such as dead algae. Most importantly, don’t forget to backwash or clean the filter so that water flows well.
Step 5: Vacuum the Pool
It is time to remove the dead algae from the pool after being killed. This is done using a manual or automatic pool vacuum to collect the debris. If your system has this option, use it along with the waste feature to suck the debris directly out and bypass the filter.
Step 6: Use an Algaecide (Optional)
You might also use an algaecide to prevent further algae blooms. That’s optional but helps, especially during warm periods. Algae grows in warm, conducive conditions with plenty of water.
Step 7: Retest the Water Chemistry
In the end, you have to check your pool's water chemistry one more time to ensure all chemical levels are back to normal. Also, the pH and chlorine levels should be monitored, and appropriate actions should be taken if there is any undesired change so that the water is not cloudy or unhealthy.
Causes of a Green Pool
Some of the common reasons why a pool turns green are:
- Low chlorine levels: Chlorine destroys algae and bacteria. When chlorine levels become too low, algae can quickly grow.
- Imbalanced pH: When pH becomes very high or low, the chlorine's strength is weakened, while the algae will overpower it.
- Poor filtration: Poor filtration occurs when a filter becomes clogged or is seldom used, allowing contaminants and algae to thrive.
- Debris Build-up: Organic debris like leaves decompose in the water, providing food for algae in the pool.
- High Temperature: Algae reproduce faster in warm and still water.
Types of Algae That Can Cause a Green Pool
- Green Algae: The most common type, where the water becomes cloudy and acquires a tinge of green.
- Yellow (Mustard) Algae: A less common type, where the algae leaves look like yellowish dust clinging to the pool's walls.
- Black Algae: The most resistant type; they form spots on walls and floors, deep in color.
By maintaining balanced pool water chemistry, proper filtering, and good cleaning habits, you may just avoid this nightmare-turning-green-pool situation.
Best Practices to Avoid a Green Pool
Cleaning and balancing a pool is not the ultimate goal; it is achieved once the clean-up has taken place. The following practices assist in preventing further green pool problems.
Routine Pool Cleaning
Use a robotic pool cleaner and/or pool skimmer to remove leaves, insects, and other pool debris daily. This will ensure that nothing continues to rot and sustain the algae.
Regular Water Testing
Check the chlorine and pH levels in your pool water at least once a week. For saturated chlorine, the optimal pH range is 7.2-7.4, which is slightly acidic.
Maintain Proper Chlorine Levels
Algae will not be a problem in the swimming pool if the chlorine content is well observed, ranging from 2-4 ppm. Proper chlorine level is vital for a clean, healthy pool. After heavy user activity or rain, raise and decrease the levels to prevent algae growth.
Wrapping It Up: Keep Your Pool Sparkling Year-Round
These steps and several other best practices will ensure that your pool is rehabilitated from green to clean and prevent future algae problems. Minimizing these maintenance services will ensure that the pool is clean and enjoyable during the summer when used heavily. Even a simple robotic pool cleaner requires less work. The vacuuming and scrubbing are all done with machines, making the work of keeping the pool free of algae very easy.