Green Pool Water
Why your pool turned green and how to get crystal-clear water back
Green pool water is one of the most common — and most alarming — pool problems in Portugal. The warm Mediterranean climate creates perfect conditions for algae blooms, which can turn a sparkling pool into a murky green pond seemingly overnight. The good news? With the right approach, your pool can be clear again within 24-48 hours.
Signs Your Pool Has Green Water
These are the telltale signs that algae has taken hold in your pool:
- Green tint visible in the water
- Slippery pool walls and floor
- Low water visibility
- Musty or swampy smell
What Causes Green Pool Water?
Green water is almost always caused by algae growth, but several factors contribute to why algae takes over:
Algae Growth
Algae spores enter the pool and multiply rapidly when conditions favor growth, especially in warm water with low sanitizer levels.
Low Chlorine Levels
Insufficient chlorine allows bacteria and algae to thrive. Common after heavy rain, high temperatures, or heavy pool usage.
Poor Water Circulation
Dead spots in pool circulation allow algae and bacteria to establish colonies, particularly in corners and behind ladders.
Metal Contamination
Metals like iron, copper, or manganese in the water source or from corroding equipment can cause discoloration.
How to Fix Green Pool Water (DIY Steps)
If the green is mild, you may be able to fix it yourself. Follow these steps carefully:
- 1
Test Water Chemistry
Use a reliable test kit to check chlorine, pH, alkalinity, and calcium hardness levels.
- 2
Shock Treatment
Add a heavy dose of chlorine shock (3-4x normal) to kill algae and bacteria. Use calcium hypochlorite for best results.
- 3
Brush Pool Walls
Vigorously brush all pool surfaces including walls, floor, steps, and behind ladders to break up algae colonies.
- 4
Run Pump 24 Hours
Keep the pump running continuously for at least 24 hours to circulate the shock treatment throughout the pool.
- 5
Vacuum Debris
Vacuum the pool floor to waste (bypassing the filter) to remove settled dead algae and debris.
- 6
Retest After 24 Hours
Test the water again after 24 hours. If chlorine has dropped significantly, repeat the shock treatment.
When to Call a Professional
If the water is dark green or you can't see the pool floor, DIY treatment may not be enough. Our technicians use commercial-grade equipment and chemicals to restore your pool in hours, not days. We also identify and fix the underlying cause so it doesn't happen again.
Green Water in Portugal
Portugal's warm summers and mild winters mean algae season is longer here than in Northern Europe. Pools in the Silver Coast and Algarve are especially susceptible due to higher temperatures and humidity. Regular maintenance through the warm months is essential.
Frequently Asked Questions
How long does it take to fix green pool water?
With professional treatment, most green pools are clear within 24-48 hours. Severe cases with dark green water may take 3-5 days with multiple treatments.
Can I swim in a green pool?
No. Green water indicates high bacteria levels and potentially harmful algae. Swimming in green pool water can cause skin rashes, eye infections, and gastrointestinal issues.
Why does my pool keep turning green?
Recurring green water usually indicates an underlying issue — inadequate filtration runtime, a faulty pump, poor circulation, or inconsistent chemical maintenance. Our team can identify and fix the root cause.
How much does it cost to fix a green pool?
Professional green pool treatment in Portugal typically costs €80-€150 depending on pool size and severity. This includes shock treatment, chemical balancing, and a follow-up visit.
Does shock treatment damage my pool?
When done correctly, shock treatment is safe for all pool surfaces. Our technicians calibrate the dosage based on your pool's volume and surface type to prevent any damage.
Need Professional Help?
Our expert technicians are ready to solve your pool problems quickly and effectively.