Nilco Angel Foam - Patio & Path Cleaner 2L Ready To Use Dirt Algae Remover - The super concentrated formula kills algae within 2 to 4 days and stays active controlling regrowth for up to 9 months - The disinfectant formula is suitable for treating all types of hard surfaces including: patio, paths, stone and driveways - Easy to use format, simply connect to a garden hose, spray and leave - The active foam formula ensures no areas are missed Perfect for large or small areas - Kills bacteria - Non-staining - Acid and bleach free