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.

The 30 SECONDS Mold and Mildew Stain Remover Concentrate is designed to kill organic growth like algae, moss, and lichen on outdoor surfaces, including roofs. Its main active ingredient is chloride, which helps eliminate these stains over time. One of its biggest advantages is the simple application method: you just spray it on and walk away—there's no need for scrubbing, rinsing, or pressure washing. This makes it ideal for homeowners who want an easy, do-it-yourself solution without hiring professionals. It works on various roof types such as composite shingles, as well as other outdoor surfaces like sealed concrete and asphalt, which adds to its versatility. Being bleach and phosphate-free with a neutral pH means it is gentler on the environment than some harsher cleaners. Coverage ranges from 200 to 600 square feet depending on how porous the surface is, which is decent for a single gallon.

Users generally rate it well, with a solid 4 out of 5 stars from over 1,800 reviewers, indicating it is effective though results take time to appear. It may not be the fastest option if you want immediate results, and since it relies on walking away after spraying, some patience is needed. Also, while it claims roof compatibility, those with delicate or unusual roof materials should double-check before use. This product suits those looking for an easy, environmentally cautious way to reduce roof algae and improve outdoor safety without heavy labor.