GreenKleen Ultimate Gel Black Spot Remover Lichen Algae Moss & Mould Killer. Black spots are lichen which thrive on stone surfaces in the damp and shady conditions. It sends out tendrils into the pores of the stone seeking nutrients from the stone. These gradually spread through the surface of the stone. Our Ultimate Gel is super strong economical formula is specially designed to kill lichen, moss, mould, and algae and remove stubborn black spots from patios, concrete and brick surfaces. It is thick unlike most other products on the market, which allows it to cling to vertical surfaces to clean hard to remove black spots which other thinner products cannot. In gel form it prolongs contact time to aid with removal. Our extra strong concentrate is double the strength of the other market leading products - How do we know? Well we used to make them! Made in the UK |