30 SECONDS, 64 oz, spray & walk away cleaner with hose end sprayer, kills lichen, moss & alga, with no pressure washing, rinsing, scrubbing, or hosing required. Simply spray & walk away. Results become visible over time. Works on many outdoor surfaces like roofs, sealed concrete, asphalt driveways & more. Bleach & phosphate free, with a neutral ph, improves traction on many surfaces, as well as appearance.