10 Best Roof Algae Cleaners 2025 in the United States

The Wet & Forget Outdoor Moss, Mold, Mildew, & Algae Stain Remover is designed to tackle green and black stains on various surfaces, including roofs, with its new and improved nozzle. The hose-end attachment can spray up to 30 feet, offering convenience for reaching higher areas. The product doesn't require rinsing, making the application straightforward. It's important to apply it on a dry surface during cool weather and ensure there’s no rain forecast within 4-5 hours.

The initial cleanup for green stains happens within 1-2 weeks, while more stubborn black stains may take several months. Long-established stains could take up to a year to clean, but surfaces can stay clean for a year or more afterward. This bleach-free and non-acidic formula is safe for use around plants, provided they are flushed with water before and after application, although you should avoid spraying near bodies of water.

The product treats up to 2,000 square feet and has an unlimited shelf life, making it a cost-effective option for heavy stained and porous surfaces. The effectiveness duration on extremely stubborn stains may require patience, and environmental precautions are essential to avoid potential harm.

Wet & Forget Outdoor Moss, Mold, Mildew, & Algae Stain Remover is a versatile multi-surface cleaner designed to easily attach to a garden hose. It uses a unique nozzle that can spray up to 30 feet, making it ideal for cleaning roofs and high areas like second-story siding. This product is quite user-friendly as it requires no scrubbing, rinsing, or pressure washing—just spray it on and let nature do the work. This is particularly convenient for those who prefer a low-effort cleaning method.

The cleaner works over time, with green stains typically disappearing within 1-2 weeks and more stubborn black stains taking several months to clear. It boasts a long-lasting effect, keeping surfaces clean for up to a year or longer. It’s essential to note that its cleaning action is gradual and may not offer immediate results for heavy stains. The product is bleach-free and non-acidic, making it safer for use around plants when precautions are followed. However, it is advised to keep it away from water sources like rivers and ponds.

It treats up to 2,000 square feet, though heavily stained or porous surfaces may require more product. Customer reviews are generally positive, with a 4.4 out of 5-star rating from over 1,200 users, highlighting its effectiveness and ease of use. On the downside, the cleaner is not instantly effective on all types of stains and may take up to a year for long-established ones to disappear. Additionally, environmental precautions must be strictly followed to avoid harming aquatic life.

Wet & Forget Outdoor Moss Mold Mildew & Algae Stain Remover is a liquid concentrate designed to tackle stains caused by moss, mold, mildew, and algae on various outdoor surfaces, including roofs. It uses a bleach-free and non-acidic formula, making it a gentler option that’s safer for plants and the environment compared to harsher chemical cleaners. The product is applied by diluting it with water and spraying it evenly on a dry, clean surface; no scrubbing or rinsing is needed, which is convenient for users who want a low-effort solution. However, it requires mild weather conditions for application and must not be used just before rain, which could affect timing and effectiveness.

The cleaning process is gradual—green algae stains may fade within 1 to 2 weeks, but tougher black stains or older buildup can take several months to disappear. Results can last a year or longer, helping to keep surfaces cleaner for extended periods. This slow action suits those who prefer a hands-off approach, though it may not satisfy users looking for quick results.

The product is compatible with a wide range of roof materials and other outdoor surfaces like wood, vinyl, aluminum, and concrete, making it versatile for different home exteriors. The coverage per container is quite generous, treating between 1,100 and 3,400 square feet depending on the surface. Users generally rate it well (4.4 out of 5 stars), appreciating its ease of use and effectiveness, though some note the wait time for full stain removal. One drawback is that established heavy stains might take six months or more to fully disappear, requiring patience. Also, careful application is necessary to avoid overspray near water sources. For those seeking a no-scrub, environmentally friendlier cleaner that works over time on roof algae and stains, Wet & Forget offers a solid, hassle-free option.