Arc Algae & Greenslime Remover is a professional, ready to use algae, moss, green patina & green deposits remover which can be used on all external surfaces such as stone, wood, plastic, glass, concrete, ceramics, paving stones, roof tiles, felt and even tarmac. It also kills red algae found on house walls and prevents recurrence. Very easy to use, can be applied by spray and it is self-acting, no need for scrubbing.