So you wake up on a sunny morning, ready for a swim… and bam — your crystal-clear pool is suddenly a swampy shade of green.  What happened? And more importantly, how do you fix it?

Don’t worry — we’ve got your back. A green pool is a common problem, especially during warm weather or after heavy rain. The good news is, with a little know-how and elbow grease, you can turn your pool from murky to magnificent in no time.

💚 Why Pools Turn Green: The Culprits

1.   Algae Overgrowth  

The  1 reason your pool turns green? Algae. Algae are microscopic plant-like organisms that love warm, untreated water. Once chlorine levels drop too low, algae can bloom — fast. A little green can become a lot of green overnight.

2.   Low or Unbalanced Chlorine Levels  

Chlorine is your pool’s best defense against algae and bacteria. When chlorine levels dip — due to heat, sun, rain, or high swimmer load — algae gets the upper hand.

3.   Poor Water Circulation or Filtration  

If your pump or filter isn’t working properly, hasn't been recently cleaned (or hasn’t run long enough), still water creates the perfect breeding ground for algae.

4.   pH or Alkalinity Imbalance  

When your pool's pH and total alkalinity are off, chlorine becomes less effective. Even with chlorine in the water, it might not be doing its job.


🧪 How to Fix a Green Pool (Step by Step)

Whether your pool is light green or full-on swamp mode, here's how to clean it up:

✅ Step 1:   Test the Water  

Use a reliable pool test kit or take a sample to your local pool store. You want to check:

• Chlorine levels
• pH and total alkalinity
• Cyanuric acid (stabilizer)

Phosphates (optional, but helpful)

✅ Step 2:   Balance the Water Chemistry  

Adjust your pH and alkalinity first. Ideal levels are: Alkalinity should always be corrected first before pH

• Alkalinity: 80–120 ppm
• pH: 7.2–7.6

📝  Pro Tip:  Shock at dusk or night — sunlight can burn off chlorine before it does its job.

✅ Step 4:   Brush and Circulate  

Algae cling to pool walls and floor, so brush all surfaces thoroughly. Run your pump and filter continuously for 24–48 hours during treatment.

✅ Step 5:   Backwash or Clean the Filter  

Your filter will be working overtime — clean it regularly to keep water moving and trap dead algae.

✅ Step 6:   Use a Pool Clarifier or Flocculant (Optional)  

If your water is still cloudy after shocking, a clarifier can help bind tiny particles so your filter can remove them. A flocculant sinks debris to the bottom, allowing you to vacuum it up.

🛡️ How to Prevent a Green Pool in the Future

  ✅ Test water   at least 2–3 times per week  
  ✅ Maintain   chlorine   levels around 1–3 ppm
  ✅ Keep pH and alkalinity in check
  ✅ Run your pump at least   8–12 hours per day   in summer
  ✅ Clean your filter regularly
  ✅ Shock weekly during heavy use or rain

 💬 Final Thoughts

A green pool may look scary, but it’s almost always fixable. The key is acting quickly and staying on top of your water chemistry. Once your pool is sparkling again, regular maintenance will keep it that way — so you can focus more on cannonballs and less on chemistry.


Need Help?

Stop by your local pool store or give us a call! Whether you need water testing, expert advice, or the right products, we’re here to help you swim happy.