Green algae on roof tiles is one of the most common problems facing UK homeowners and professional contractors alike. The damp, temperate British climate creates ideal conditions for algae, mould, and other biofilms to take hold, and once established, they can cause discolouration, contamination, and surface degradation if left untreated.
The good news is that with the right biocide cleaner, removal is straightforward, and you can prevent rapid regrowth at the same time.
Why Algae Grows on Roof Tiles
Roof tiles are particularly vulnerable to biological growth. Moisture retention, shade, and the textured surface of concrete, clay, and slate tiles all provide the conditions algae and biofilms need to establish. Over time, green algae, black mould, and lichen can cause visible discolouration and contamination across large surface areas.
Pressure Washing vs Biocide Treatment
Many people reach for a pressure washer as a first instinct, but for roof tiles, this is often the wrong approach. High-pressure water can damage tile surfaces, force water beneath tiles, and only addresses the visible growth rather than killing it at the source. The result is typically rapid regrowth.
A professional biocide cleaner works differently. It penetrates and kills algae, mould, and biofilms at the root, and offers residual benefits that slow regrowth, meaning the surface stays cleaner for longer after treatment.
Removing Roof Algae with AlgoClear Pro
AlgoClear Pro is a high-strength, professional concentrated biocide cleaner, HSE-registered and specifically suited to roof cleaning, as well as patios, driveways, render, and sports surfaces such as tennis courts.
ProGreen is the exclusive UK distributor of AlgoClear™.
What makes it different:
- Contains no bleach, acids, or ammonia, with no risk of staining or damage to tile surfaces
- The active ingredient DDAC is a compound derived from naturally occurring plant oils
- DDAC remains fully effective in hard water. Many competitor products use active ingredients that bind with minerals in hard water, significantly reducing their efficacy. AlgoClear Pro does not suffer from this and retains full efficacy regardless of water hardness
- HSE-registered biocide, recognised for professional use
- Offers residual benefits, helping to prevent slippery green biofilms from returning quickly after treatment
How to Apply AlgoClear Pro to Roof Tiles
The right equipment depends on whether you are treating your own home or working professionally across multiple properties.
For domestic and homeowner use:
- Softwash Starter Kit - a complete electric backpack system with 5.4m telescopic lance and 6m hose, allowing roof treatment from ground level without ladders
For professional or large-area applications:
- AlgoClear Softwash Delivery System Dosing Box - for accurate, controlled dilution and application
- 6.5m Telescopic Lance - for extended reach
- Scraper Head - for mechanical removal where needed
Important application notes:
- AlgoClear Pro can be used all year round
- Results may be affected if rain occurs within 24 hours of application
- Results may be affected if temperatures are below 8°C at the time of application
Frequently Asked Questions
Is AlgoClear Pro safe on all roof tile types?
AlgoClear Pro treats hard surfaces with no risk of staining or damage, and contains no bleach, acids, or ammonia.
Is there a domestic version available?
Yes, AlgoClear (without the Pro designation) is available for domestic use.
Why does the product colour vary?
There may be some colour variation between bottles, ranging from clear to yellow. This is within product specifications and does not affect efficacy in any way.
Summary
For professional roof algae removal, a biocide treatment with AlgoClear Pro offers a safer, more effective, and longer-lasting result than pressure washing alone. Its hard water stability, HSE registration, and residual protection make it particularly well suited to UK conditions and professional contractor use.
Shop AlgoClear Pro, available in 5L and 10L from ProGreen, the exclusive UK distributor.
For more information on cleaning moss, algae and lichen from hard surfaces, read our helpful guide.
