Join Date: Feb 2006
Location: Mid Norfolk
Thanked 65 Times in 56 Posts
I used "Patio Magic" (on the patio!) last year. It was so slow that I forgot what the stones looked like and they were very dirty again so I couldn't decide if it worked or not. Next time I might take photos.
I also bought a different product (name forgotten but I could go out to the shed and look if it wasn't raining heavily) which contained a mixture of "magic" chemicals but smelt strongly of bleach and cost £25 per 5litres. This got rid of much of the horrible black marks which apparently is algae growing inside the stone, but so did a bottle of cheap bleach from Lidl.
Would I try these on the MH roof? Perhaps, but I'm happy for someone else to do it first.