30 SECONDS Spray & Walk Away, 1 Gallon - Concentrate 30 SECONDS Spray & Walk Away kills lichen, moss and algae No pressure washing, rinsing, scrubbing, or hosing required. Simply spray and walk away. Results become visible over time Works on many outdoor surfaces like roofs, sealed concrete, asphalt driveways and more Bleach and phosphate-free, with a neutral pH Improves traction on many surfaces, as well as appearance