Why Is My Pool Green After Rain? 💧🌧️

A relaxing dip in your backyard pool can quickly lose its appeal when you wake up to a murky, green mess after a night of rain. But don’t worry—you’re not alone. A green pool after heavy rain is a common issue for pool owners across Australia, especially during stormy seasons. Let’s dive into what causes it and how to fix (and prevent) it.

🌿 Why Does Rain Turn My Pool Green?

1. Algae Love Rainwater
Rain brings fresh water—and with it, nutrients. Unfortunately, these nutrients (like phosphates and nitrates) are exactly what algae thrive on. When the rain dilutes your pool’s chlorine levels and feeds the algae, you’ve got the perfect storm for a green pool.

2. Lowered Chlorine Levels
Chlorine is your pool’s primary defense against contaminants. Rainwater can both dilute chlorine and introduce new contaminants, making it harder for your pool to stay sanitised.

3. pH and Alkalinity Imbalance
Heavy rain can cause your pH and alkalinity to crash. When these levels are out of balance, your chlorine becomes less effective—even if it’s present in the right amount.

4. Runoff and Debris
Rain often washes leaves, soil, and other organic matter into your pool. This not only makes the water dirty but also consumes chlorine as it works to break down all that organic waste.

🧪 How to Fix a Green Pool After Rain

Step 1: Test the Water
Use a pool test kit or bring a sample to Pool Perfectionists for a free water analysis. Check:

• Chlorine
• pH
• Total Alkalinity
• Phosphates

Step 2: Balance Chemicals
Start by correcting pH and alkalinity. This helps chlorine work more effectively.

Step 3: Shock the Pool
Add a chlorine shock treatment to kill off any algae spores and bacteria. Be generous—rain usually introduces more contamination than you think.

Step 4: Brush and Circulate
Scrub the walls and floor to break up algae and allow chlorine to penetrate it. Run your pump and filter continuously until the water clears.

Step 5: Vacuum and Backwash
Vacuum the debris and dead algae from the bottom. Don’t forget to clean or backwash your filter afterward—it’s been working overtime.

🛡️ How to Prevent a Green Pool After Rain

• Keep your chlorine levels in check: Consider a salt chlorinator or automatic dispenser to maintain consistent sanitation.
• Use a pool cover before storms: Especially if you know bad weather is on the way.
• Trim overhanging trees: Less debris = fewer problems.
• Add algaecide before big rains: A preventative dose can keep algae from taking hold.
• Invest in regular water testing: At Pool Perfectionists, we offer free testing to keep your pool healthy all season long.

💡 Final Tip: Don’t Let Rain Ruin Your Pool

A green pool is treatable, and with a little prep, it’s totally preventable. If you’re unsure where to start, stop by Pool Perfectionists for expert advice, quality chemicals, or even a one-off recovery service.

Need help? Book a post-storm pool check or let us clean it for you. We’ll get your pool back to blue—fast.