Wash Safe Industries TILE ROOF WASH Premium Eco-Safe and Organic Tile Roof Cleaner, 10 lb Container Use to clean stains caused by mold, mildew, black algae, fungus, moss, dirt or grime from concrete, clay or slate roof tiles Tile Roof Wash is made from earth friendly hydrogen peroxide and it will not harm people, pets, plants or property As an oxygen based cleaner, the product only has an active life of 4-6 short hours before this product biodegrades A clean roof greatly improves the value of your home Once your roof is clean, just apply annually and let the rain rinse it off to maintain a clean roof forever