10 Best Roof Algae Cleaners 2025 in the United States

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.

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 Moss, Mold, Mildew, & Algae Stain Remover is a concentrate designed to clean outdoor surfaces including roofs without scrubbing or rinsing. It uses a bleach-free formula that works with rain and wind to slowly remove stains caused by moss, mold, mildew, and algae. You dilute the concentrate with water and apply it using a garden sprayer to dry, debris-free surfaces, preferably in mild weather and away from water sources to protect plants.

The cleaning process is gradual — light green stains may clear in 1-2 weeks, while tougher black or old stains can take several months or up to a year. The product is compatible with hard, sealed, non-porous surfaces, making it suitable for many roof materials but less so for porous ones which absorb more product and may need more applications. Each bottle treats between 375 and 1,125 square feet depending on stain severity.

Environmental impact is minimized by the bleach-free formula, but caution is still needed near plants and water. The ease of application and no-rinse approach make this cleaner a good choice for those seeking a low-effort solution for maintaining clean roofs and outdoor surfaces, especially when planning ahead for its slower action.