If you’ve ever wondered how to clean a green pool, you’re not alone. Thousands of Aussie pool owners face this issue every year—especially after storms, long holidays, or broken pool filters. A green pool is not only unpleasant to look at, but it’s also a sign that your water is unsafe for swimming. The green tint is often due to an overgrowth of algae, poor filtration, and low chlorine levels.

This guide will walk you through the essential steps to bring your backyard pool back to its sparkling, swimmable glory. Whether you’re a new pool owner or someone who’s battled murky water before, these tips will help get you sorted.

Key Takeaways

• A green pool is mainly caused by algae due to low chlorine or poor circulation.
• It’s essential to balance your pool water before applying any treatment.
• Chlorine shock treatment is effective in eliminating algae and bacteria.
• Adjusting pH levels is a critical step before sanitising the water.
• Brushing and vacuuming the pool helps remove visible algae and debris.
• Brown algae are more stubborn and may require additional cleaning steps.
• In extreme cases, a complete surface cleaning may be necessary.
• Monitoring chlorine levels ensures proper sanitisation and prevents regrowth.
• Running the filtration system continuously is crucial after treatment.
• Weekly maintenance and regular testing can help prevent future problems.

Why Does a Pool Turn Green?

A green pool is typically the result of algae, which thrives in warm, stagnant water with low sanitiser levels. When chlorine levels drop too low, it creates the perfect breeding ground for algae to bloom.

Other causes include:

• Broken or dirty pool filters
• Unbalanced pH levels
• Lack of circulation
• Warm weather and organic debris buildup

Assessing the Severity of the Problem

Before diving into treatment, assess how green the water is:

• Light green: Early stages of algae growth.
• Dark green: Moderate algae bloom, needs shock treatment.
• Black-green or murky: Severe, likely needs aggressive cleaning or acid wash.

Gather Your Supplies

To clean your green pool efficiently, you’ll need the following equipment and chemicals:

• Pool water test kit
• Pool brush and vacuum
• Algaecide
• Liquid chlorine for pool sanitisation
• Pool shock treatment
• Filter cleaner
• Leaf skimmer or net
• Flocculant (if water is cloudy)
• Safety gear like gloves and goggles

Use of Hydrochloric Acid for Pool Balancing

One critical step many pool owners overlook is water balancing before shocking. If your pH is too high or too low, chlorine won’t be as effective. You may need to add hydrochloric acid for pool water balancing to bring the pH into the ideal range of 7.2–7.6. This ensures your chlorine can do its job properly.

Step-by-Step Guide on How to Clean a Green Pool

Step 1: Remove Debris

Start by skimming out leaves, insects, and organic matter from the pool. This will prevent added strain on your filter and improve chlorine efficiency.

Step 2: Test the Water

Use a reliable test kit to check the following:

• pH level
• Alkalinity
• Chlorine levels
• Stabiliser (CYA)

Adjust your pH and alkalinity as needed before moving forward.

Step 3: Brush the Pool Walls and Floor

Algae often cling to pool surfaces. Use a sturdy pool brush to scrub all areas of the pool—steps, floor, walls, and around ladders.

Step 4: Shock the Pool

Shock your pool with a heavy dose of chlorine. For this, use liquid chlorine for pool sanitising. Follow the manufacturer’s dosage for your pool size and the severity of the algae bloom.

Shock treatment will kill most algae, bacteria, and other contaminants in the water.

Also Read: Self-Cleaning Pool

When You Need a Pool Cleaning Acid Wash?

In extreme cases where water clarity is too poor, or algae keeps returning, a pool cleaning acid wash may be necessary. This involves draining the pool and using a diluted acid solution to remove stubborn algae and stains from the pool surface.

What About Brown Algae?

If you’re dealing with brown algae in swimming pool, it may be more resistant to chlorine. Brown algae are harder to remove and may require brushing, followed by algaecide and shock treatment. They cling tightly to pool walls and may reappear quickly if not fully eradicated.

Run the Filter System Continuously

After shocking the pool, run the filter continuously for at least 24–48 hours. This helps to circulate chemicals and filter out dead algae. Make sure your filter is clean and in good working condition.

Vacuuming the Pool

Manual vacuuming will remove dead algae that settles on the floor. Automatic pool cleaners may stir up debris rather than remove it.

You can vacuum:

• Directly to waste if your system allows
• Using a sand or cartridge filter

Use Flocculant for Cloudy Water

If the water remains cloudy even after shock and filtration, use a flocculant. It clumps small particles together so they can be vacuumed easily.

Clean or Backwash the Filter

Your filter will be lifting the heavy during this process. Depending on your filter type:

• Cartridge filter: Remove and rinse thoroughly.
• Sand filter: Backwash as needed.
• DE filter: Backwash and recharge with DE powder.

Monitor Chemical Levels Daily

For the next few days, test the water daily and make sure levels stay within range. Rebalance as needed.

Increase Free Chlorine in a Swimming Pool

If your tests show low active chlorine, you’ll need to know how to raise free chlorine in a swimming pool. This can be done by adding stabilised chlorine or more liquid chlorine until levels are adequate—typically 1–3 ppm for regular use and up to 10 ppm for shock treatments.

Preventing Future Green Water

To avoid green pool disasters in the future, follow these tips:

• Keep chlorine levels consistently in the range
• Run your filter daily for 8–12 hours
• Clean your skimmer and filter regularly
• Remove debris quickly
• Use algaecide periodically
• Shock your pool weekly in hot weather

Quick Checklist for Weekly Pool Maintenance

• Test pH, chlorine, and alkalinity
• Skim debris daily
• Brush walls and floor weekly
• Vacuum once a week
• Run the filter system
• Clean filter monthly

FAQs

1. Can I swim in a green pool?

No, swimming in a green pool is unsafe. It may contain harmful bacteria, pathogens, and algae that can cause skin, ear, or eye infections.

2. What is the fastest way to clean a green pool?

The fastest way is to shock the pool with chlorine, balance pH levels, brush surfaces thoroughly, and run the filter non-stop for 24–48 hours.

3. How do I make my green pool blue again?

Balance the water, shock it with chlorine, clean the surfaces, run the filter continuously, and use a flocculant if needed for cloudy water.

4. Can too much chlorine make a pool green?

While rare, too much chlorine can react with metals in the water and cause a greenish tint. Always test and adjust chemical levels as needed.

5. Will baking soda clear a green pool?

Baking soda helps raise alkalinity and pH but won’t kill algae or clear a green pool on its own. You’ll still need chlorine and proper filtration.

Conclusion

Now that you know how to clean a green pool don’t wait until it gets worse. With the right steps, a little patience, and consistent upkeep, you’ll have that crystal-clear blue water again in no time. Whether you’re dealing with a light green haze or a full-blown algae swamp, follow this guide to make your pool the summer oasis it should be.