Green pool? Don't panic. Follow this step-by-step guide to shock, filter, and clear your pool fast — with NZ product recommendations from Splash Water Specialists.

Opened up your pool after winter and found a swamp? Or maybe a few days of warm weather and no chlorine turned your pool green overnight? Don't panic — a green pool is one of the most common pool problems in New Zealand, and it's fixable. Here's exactly what to do.

Why Does a Pool Turn Green?

Green water is almost always caused by algae growth. Algae thrive when:

• Chlorine levels drop too low (below 1 ppm)
• pH is out of range, making chlorine less effective
• The pool hasn't been circulated or filtered properly
• After heavy rain, which dilutes chemicals and introduces contaminants

Step 1: Test Your Water

Before adding anything, test your water to understand what you're dealing with. Check pH, alkalinity, and chlorine levels. If you're unsure, bring a sample into Splash Water Specialists for a $6.00 test or free when you spend $30.00 in store on the same day

.

👉 Shop Pool Water Testing Kits

Step 2: Balance pH and Alkalinity

Chlorine only works effectively when your pH is between 7.2 and 7.6. If your pH is off, fix it first before shocking the pool — otherwise you'll waste chemicals.

👉 Balance Pak 100 – Alkalinity Increase
👉 Shop All Pool Balancers & Chemicals

Step 3: Shock the Pool

Shocking means adding a large dose of chlorine to kill the algae. For a green pool, you'll typically need to "super-chlorinate" to 10–20 ppm — far above the normal 1–3 ppm maintenance level.

• Use granular chlorine (dichlor) or liquid chlorine for fast results.
• Add the shock in the evening to prevent UV from burning it off before it can work.
• Run your pump continuously for at least 24 hours.

👉 Swim Clear Granulated Pool Chlorine (Dichlor)
👉 Liquid Pool Chlorine (Click & Collect)

Step 4: Run Your Filter Continuously

Your filter is doing the heavy lifting — it's removing the dead algae from the water. Run it 24/7 until the water clears. Backwash or rinse your filter regularly during this process, as it will clog quickly.

Step 5: Brush the Pool Walls and Floor

Algae clings to surfaces. Brush the walls, floor, and steps thoroughly to dislodge it so your filter and chlorine can do their job. Do this daily until the pool clears.

Step 6: Vacuum to Waste

Once the algae starts dying (it will turn grey/white), vacuum the pool to waste rather than through the filter to avoid clogging it. If you don't have a manual vacuum, a robotic pool cleaner can help speed up the process.

👉 Shop Dolphin Pool Cleaners

How Long Does It Take?

A mildly green pool can clear in 24–48 hours. A severely green pool (where you can't see the bottom) may take 3–5 days of continuous treatment. Be patient and keep the pump running.

Preventing It From Happening Again

• Test and dose your pool 2–3 times per month during summer.
• Keep chlorine above 1 ppm at all times.
• Run your pump at least 8 hours per day.
• Use slow-release chlorine tabs for consistent sanitisation between treatments.

👉 Pacific Blue Power Tabs – Slow Release Chlorine

Still Struggling?

If your pool won't clear after several days of treatment, come in and see us. We'll test your water and help you get to the bottom of it.

👉 Browse All Pool Chemicals

Tags

algae chlorine green pool how-to pool care pool maintenance pool shock

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