We might like our grass to be green and maybe our apples. But we certainly don’t like our swimming pool water green!
Green swimming pool water is every pool owner’s nightmare. Not least because it is unsightly, unhealthy, and often shows up just before a planned pool party!
Whether it’s caused by algae growth, poor filtration, or chemical imbalance, getting back to crystal clear water can seem an impossible task. The good news, however, is that you can fix green pool fast, often within 24 hours.
At Splash in Style Pool Builders, we not only build beautiful pools. We also offer expert pool servicing to help get rid of your green pool water quickly.
Key Takeaway
To fix green pool water fast, act quickly with the right chemical treatment, filtration, and brushing. That said, prevention through regular maintenance is the key to keeping your pool crystal clear.
Why Is Your Pool Green?
A green pool is a sign that something’s gone wrong beneath the surface. Therefore, understanding what causes your pool water to turn green is the first step to getting it clean again fast.
Poor Circulation or Filtration
When your pool pump or filtration system isn’t working properly, it allows dirt, oils, and algae spores to hang around longer than they should. Over time, this leads to floating debris, cloudy water, and eventually a full-blown green pool.
Clogged pool filters, dirty media filters, or a broken pressure gauge can all contribute to the issue. Subsequently, running a well-functioning filtration system is essential to keeping the water moving and preventing algae from settling on the pool walls or pool floor.
Imbalanced Chemicals
Your pool water needs the right chemical balance to stay clean and safe. When pH levels or alkalinity go off, it can cause your pool to turn green.
However, the wrong chemical dosage, whether too much or too little, can prevent sanitising chemicals from doing their job properly. Inconsistent maintenance or adding the wrong products can also throw your water chemistry off, which will allow green algae to flourish.
Low Sanitiser Levels (Chlorine or Salt)
If your free chlorine levels are too low or if your salt chlorinator is not producing enough sanitiser, algae can take over in no time.
Without enough chlorine or salt, algae growth happens fast, especially in warm water. The good news is that this one of the most common causes of a green pool, and one of the quickest to fix.
Algae Growth After Rain or Heatwave
Heavy rainfall or a hot weather spike can throw everything out of balance. Unfortunately, rain adds contaminants and dilutes your chemicals, while heat speeds up algae outbreaks. This can result in a sudden greenish hue to your water developing, sometimes overnight.
Can You Swim in a Green Pool?
It’s best to avoid swimming in a green pool, no matter how tempting it looks on a hot day. Green water often means algae, bacteria, and a possible chemical imbalance, which can irritate your skin, eyes, and even make you sick.
For these reasons, until your pool is clear, sanitised, and properly balanced, it’s safest to stay out of it.
How to Fix a Green Pool Fast: Step-by-Step
Fixing a green pool quickly is possible, but it takes a little know-how, elbow grease, and the right pool chemicals. Follow these steps to enjoy crystal clear water again.
Step 1: Test Your Pool Water First
Before reaching for the chlorine, take a water sample and test your pH levels, free chlorine, and alkalinity. This gives you a clear picture of the problem, whether that be low sanitiser, chemical imbalance, or both.
You can use a home test kit or have it checked by a professional like Splash in Style Pool Builders.
Step 2: Lower the pH Level
A high pH makes chlorine less effective. So, if your pH is above 7.6, you will need to bring it down to around 7.2 for the shock treatment to work properly. Depending on your pool type, you can even add a pH reducer or baking soda in the appropriate dosage.
Step 3: Shock the Pool with Chlorine
Now is the time to hit the algae hard. Add a green pool treatment with a strong chlorine shock, using up to 3–5 times the normal amount (depending on how dark green the pool water is). This step will kill algae, neutralise bacteria, and start clearing the green tint.
Step 4: Brush Walls and Vacuum Debris
Use a sturdy pool brush to scrub the pool walls, steps, and pool floor, especially areas where algae tend to cling. Once brushed, manually vacuum out the dead algae, algae particles, and any floating debris. This helps to speed up the cleaning process.
Step 5: Run the Pump & Backwash the Filter
Turn your pool pump on and let it run for 24 hours straight. This keeps the water circulating and moves the dead algae into your system filtration. Don’t forget to backwash the filter and clean your cartridge to remove built-up debris.
Step 6: Repeat as Needed Until Water Clears
Depending on the severity of the algae problem, you may need to repeat shocking and brushing over the next day or two. But in most cases, you’ll see major results (and a nearly clean pool) within 24 hours.
Green Pool Treatment Based on Severity
The level of algae growth and water clarity can help determine how aggressive your green pool fix needs to be. Use these colours as a guide:
Light Green (Mild Algae Bloom)
Add a standard dose of chlorine shock and run the pool pump continuously for 12–24 hours. Brush the pool surface thoroughly.
Mid-Green (Moderate Bloom)
Double the chlorine dosage, lower pH levels, and backwash filters more frequently. Scrub and vacuum all surfaces.
Dark Green (Severe Algae Overgrowth)
Triple shock your pool water, use a pool algaecide, and clean filters twice. Consider professional help for full green pool recovery.
Treatment Advice Based on Filter Type
Your filtration system plays a key role in how quickly you can fix a green pool. Each filter type has its own cleaning process.
Cartridge Filters
Remove the cartridges and rinse them thoroughly after shocking. You may need to clean them multiple times during the green pool treatment.
Sand or DE Filters
Backwash frequently to clear out algae particles and debris. If the green water persists, check that the media filters are not clogged.
Types of Green Pool Water Algae and How to Kill Them
Each type of algae behaves differently and requires a specific treatment plan. So, knowing what you’re dealing with will help you choose the most effective green pool treatment.
Green Algae
This is the most common type and usually floats in the water or clings to walls. It is easily treated with chlorine shock treatment, brushing, and good filtration.
Yellow/Mustard Algae
This colour algae to shady corners and resists standard treatment. Use a strong algaecide and brush surfaces thoroughly to get rid of it.
Black Algae
Stubborn and rooted in pool walls, such algae requires aggressive scrubbing, triple shock, and specialist chemicals to kill it completely.
Best Practices to Prevent a Green Pool
The best way to keep your pool water clean and clear year-round is prevention. Here’s how to stop it from turning green in the first place.
Regular Testing & Chlorine Maintenance
Check your chlorine levels, pH, and alkalinity at least twice a week, especially in summer. Using the proper amount of chlorine helps prevent pool algae from taking hold. If your pool water turns green, it’s often because sanitiser levels dropped too low.
Weekly Brushing and Skimming
Brush walls and steps to remove algae spores before they spread. Skim leaves and debris regularly to keep your pool clean, as organic matter feeds algae growing in varying degrees.
Maintain Pump & Filter Health
A well-maintained filtration system prevents algae outbreaks. Backwash your filter, clear out baskets, and check your pump is circulating water properly. For added clarity, try adding baking soda. You’ll be surprised how quickly baking soda clears minor cloudiness and keeps your pool clear for longer.
