Preventer All Stone Types – Maintain Natural Colour, Prevent Regrowth of Black Lichen, Slippery Green & Red Algae, and White Fungi – Spray and Leave Patio and Driveway Cleaner – 2.5L

This product worked perfectly, does exactly what it says on the label. My slabs looked really bad but now look like new. Really pleased how good they look. I needed to go over them a couple of times but definitely worth it. I have also brought the preserver and will use before winter

The product must be reapplied each year, so is expensive but worth it to keep the patio looking new

OK product. Other alternatives in the market that is much cheaper.

I've used this for many years and it does exactly what it says

Very pleased with this product as it worked very well

It works!!

I think as a prevention it is good but do not expect it to clean anything except green algae. Considering both the remover and preventer are very expensive I would use the remover and not bother about the preventer unless you don't mind using something else to clean it first, which of course adds to the cost and work. The remover is good but as I say a costly exercise. You have to use it for at least 3 years if not longer to get rid of the black spot if it is bad.