MegaSack DRAW - This year's winner is user - rgwb
We will be in touch
Me again. The patio is suffering from black spot, pretty badly in places. I've never used chemicals and don't intend on starting but it's looking pretty grotty. Looking at stuff to get rid of black spot but it's just nasty chemicals.
The patio drains towards the grass* so I guess it may just be something I have to live with, also we have frogs under the big planter so another reason to avoid putting anything nasty down. I've seen some people advocating vinegar or bicarb and a bit of elbow grease. I'd be up for that if I knew I could get a result. Can always try a patch.
*yeah, I know, the grass is already a state (as is the planter). It is winter though...
Wet and forget. Won't give instant results, but it does work if you let it. Apply twice a year with a garden/ fence pump sprayer and let it do its thing. Safe for pets.
I bought some concentrate years ago, which I think will outlast me.
https://www.wetandforget.co.uk/wet-forget-mould-lichen-algae-remover
Pic looks fine to me - stone will always weather and stuff will grow on it so unless it's a slip hazard I'd just leave it.
Wet and forget. Won’t give instant results, but it does work if you let it. Apply twice a year with a garden/ fence pump sprayer and let it do its thing. Safe for pets.
Just bought some to try...
I can't see much other than normal weathering either. If you want to clean the surface on a relatively small area like that how about a scrubbing brush, water, and sharp sand as an abrasive.