This convenient 32 oz. ready-to-use premixed formula removes green and black algae, mildew, fungus, and lichen stains from roofs, siding, decks, brick, stucco, and other exterior surfaces. It is biodegradable, noncorrosive, and does not require damaging power washing and/or brushing techniques, in fact no rinsing is required. Spray & Forget does not contain any bleach, chlorine, lye, heavy metals, or acids. Simply spray it and forget it.