How to Stop Algae and Fungus Coming Back on Exterior Walls
Kill algae and fungus for good, and stop them returning every monsoon.
Short answer: Algae and fungus return because the old growth was painted over, not removed, and because the wall stays damp. To stop it for good, wash off all green and black growth, treat the surface with a fungicidal wash, let the wall dry, then repaint with an antimicrobial exterior emulsion like More Life or the premium Majestic with Nano Bio-Shield. Fixing the moisture source, shade and poor drainage, is what keeps algae from coming back season after season.
Why does algae and fungus keep coming back on my walls?
Algae (the green film) and fungus or mould (the black and grey spots) are living organisms that need moisture, warmth, and a food source to grow. Kerala provides all three in abundance: high humidity, warm temperatures, and long monsoon wetness. When you simply paint over existing growth, the spores survive underneath and push straight back through the new coat within a season.
The two most common reasons algae returns are incomplete removal and unresolved dampness. If any green or black remains before you repaint, it will regrow. And if the wall stays wet, from shade, poor drainage, splashing gutters, or a north-facing aspect that never sees direct sun, new spores will colonise even a fresh antimicrobial coat faster. Killing the growth and drying the wall are both essential.
How do you remove algae and fungus properly?
Removal must be thorough. Follow these steps in order:
| Step | Action | Why it matters |
|---|---|---|
| 1. Scrub | Wet the wall and scrub off all visible green and black growth with a stiff brush | Removes the living surface layer |
| 2. Fungicidal wash | Apply a fungicidal or bleach solution, leave 15 to 20 minutes | Kills spores left in the pores |
| 3. Rinse and dry | Rinse clean and let the wall dry fully, 24 to 48 hours | Paint will not bond to a wet or contaminated wall |
| 4. Repaint | Apply an antimicrobial exterior emulsion in two coats | Adds a protective, growth-resistant film |
Do not skip the fungicidal wash. Scrubbing alone leaves microscopic spores in the plaster that regrow within weeks. Let the surface dry completely before painting, because trapped moisture is exactly what algae needs.
Which paint resists algae and fungus best?
After cleaning, the paint you choose decides how long the wall stays clear. More Life is a tropical-weather emulsion that is dirt-proof, scrub-resistant, and antimicrobial, built specifically for high rainfall and heat. It resists the microbial growth that thrives in Kerala’s climate and carries a 5 Year Warranty.
For the highest level of protection, Majestic is the premium exterior emulsion with Nano Bio-Shield and Lotus Effect self-cleaning technology. The Lotus Effect makes water bead and roll off, carrying dirt and spores with it, so the wall stays cleaner and drier. Nano Bio-Shield actively resists algae and fungus. Majestic carries a 12 Year Warranty and is the best choice for shaded or north-facing walls that are most prone to regrowth.
How do you stop algae from ever coming back?
Paint alone is not enough if the wall stays wet. Reduce the moisture that feeds the growth. Trim back trees and shrubs touching the wall so air and sunlight reach it. Fix leaking gutters and downpipes that keep a section constantly wet. Redirect splashing water away from the base of the wall. Where a wall never sees direct sun, a self-cleaning paint like Majestic is worth the investment because it keeps the surface drier between rains.
Combine three things and algae will not return: complete removal with a fungicidal wash, an antimicrobial or self-cleaning topcoat, and fixing the dampness source. For walls that are also damp from seepage, treat the moisture first using the methods in our guide on stopping wall dampness before the monsoon, then repaint.
Lotus Effect self-cleaning, Nano Bio-Shield and a crack-resistant film.
12-Year WarrantyView Majestic →
Dirt-proof, scrub-resistant and antimicrobial for high rainfall and heat.
5 Year WarrantyView More Life →Frequently asked questions
Why does algae grow back even after I repaint?
Because the old growth was painted over instead of removed, or the wall stays damp. Spores survive under fresh paint and push back through. Always scrub off all growth, apply a fungicidal wash, dry the wall, then repaint with an antimicrobial emulsion.
Does antimicrobial paint alone stop algae?
It helps a lot, but not if the wall remains wet or the old spores were not killed. Antimicrobial and self-cleaning paints like Majestic and More Life resist growth, but you must first remove existing algae and reduce the moisture source for a lasting result.
Can I use bleach to clean algae off my wall?
Yes, a diluted bleach or a dedicated fungicidal wash works well to kill spores. Apply it after scrubbing off visible growth, leave it 15 to 20 minutes, then rinse. Wear gloves and eye protection and keep it off plants. Let the wall dry fully before painting.
Which walls get algae the most in Kerala?
North-facing and shaded walls that never get direct sun, walls under trees, and walls kept wet by leaking gutters or splashing water. These stay damp longest and grow algae fastest. They benefit most from a self-cleaning paint like Majestic plus better drainage and sunlight.
How often should I repaint to keep algae away?
With proper removal and a quality antimicrobial coat, exterior paint can stay clear for several years. Majestic’s 12 Year Warranty and More Life’s 5 Year Warranty reflect their durability. Inspect yearly, wash the walls occasionally, and address any new damp sources early.
Keep your walls clean, season after season
Remove the growth, kill the spores, fix the damp, and finish with a self-cleaning or antimicrobial Turbolux emulsion. Your walls stay bright through the monsoon.
Find your Turbolux paint →Made in Kerala for Kerala’s climate.
Turbolux Paints
July 18th, 2026