DOFF Super Concentrate Path, Patio & Decking Cleaner gives visible results in just 1-2 days. Removes mould, mildew and algae from most hard outdoor surfaces. No scrubbing and no rinsing is required, simply apply and walk away. Results may last for up to 1 year. Concentrated formula makes up to 12 litres of solution. Contains Benzalkonium Chloride.