Green Gone Outdoor Algae, Mould & Lichen Killer 750ml. The appearance of green algae/lichen on property substrates and in a garden environment is generally viewed as unsightly, it can also be potentially dangerous on pathways/walkways due to its slippery characteristics. The effectiveness and ease of application of Green gone has the great attraction in that no physical work is required, no scrubbing, brushing, pressure washing or rinsing in order to achieve the removal of green organic growth from all types of hard surfaces. Just apply to the area and leave# the results will be visible within 36 hours and it protects against re-growth for up to 9 months. Green gone can be used on all hard outdoor surfaces such as paved areas, patios, driveways, block pavers, fencing, decking, steps, sheds, glass, UPVC windows, greenhouses, Perspex, garden furniture, walls, roofs, terracotta pots, in fact any surface that will allow green algae/lichen to grow. 750ml is sufficient to treat up to 10 sq.mt. Contains Benzalkonium Chloride 1.0%w/w.