How Do I Get Rid of Algae in My Pool?

Algae blooms can turn your pool from inviting to unswimmable in no time (well, you can technically swim in it, but would you WANT to?)—especially in Australia’s warm climate. While prevention is best, here’s a step-by-step guide to tackle green, yellow (mustard), or stubborn black algae and restore your pool’s sparkle.

Step 1: Identify the Algae Type

Green Algae: Cloudy water with slimy green patches (most common, easiest to treat).
Yellow/Mustard Algae: Dusty yellow spots on walls or corners (resistant to normal chlorine levels).
Black Algae: Dark, speckled spots with deep roots (common in porous surfaces like concrete).

You can check out the full algae busting guide here if you need more details.

Step 2: Gear Up

You’ll need:

A sturdy pool brush (stainless steel for concrete, nylon for vinyl/fibreglass).
Pool shock (granular chlorine or non-chlorine shock).
Algaecide (copper-based for green/yellow algae; specialised “black algae” formula for stubborn cases).
Test kit to monitor chemical levels.
Vacuum and filter for cleanup.

Step 3: Scrub & Vacuum

Green/Yellow Algae: Brush walls, floors, and corners vigorously to break up the biofilm.
Black Algae: Use a wire brush (for concrete) to scrape off the protective outer layer—this lets chemicals penetrate the roots.
Vacuum debris to waste (avoid recirculating dirty water).

Step 4: Shock the Pool

Green Algae: Add double the usual dose of chlorine shock (aim for 10–20 ppm free chlorine).
Yellow Algae: Use triple the dose (chlorine-resistant, so aim for 20–30 ppm).
Black Algae: Shock at 30+ ppm and repeat if needed.
Pro tip: Shock at dusk to prevent UV from burning off chlorine.

Step 5: Apply Algaecide

Green/Yellow Algae: Add an algaecide post-shock to prevent regrowth. (Water TechniX Algaecide)
Black Algae: Use a black algae-specific algaecide containing penetrating agents. (Water TechniX Black Spot Remover)
Always follow label instructions—overdosing can stain surfaces!

Step 6: Run the Filter & Retest

Run the filter 24–48 hours to circulate chemicals and clear dead algae.
Backwash/clean the filter once pressure rises by 10–15 kPa.
Retest water after 24 hours: adjust pH (7.2–7.6), chlorine (1–3 ppm), and alkalinity (80–120 ppm).

Step 7: Prevent Future Blooms

Maintain chlorine levels: Never let it drop below 1 ppm.
Brush weekly: Especially in shaded areas where algae thrive.
Use preventative algaecide: Add a weekly dose during peak season.
Check stabiliser / sunscreen (CYA): Keep 30–50 ppm to shield chlorine from UV rays.

When to Call a Pro

If algae returns repeatedly (could indicate filtration issues or phosphate buildup).
For black algae in fibreglass pools (aggressive scrubbing risks surface damage).

Need Algae-Fighting Products?

Browse our Algaecides & Pool Shocking Products for fast-acting treatments. Pair with a good brush and test kit to stay ahead of blooms.

Final Tip: Algae thrives in neglect—stay consistent with testing and cleaning, and your pool will reward you with hassle-free swims all summer long!

How Do I Get Rid of Algae in My Pool?Updated a month ago