Moss remover on Indian sandstone

BurntAsh

I've just powerwashed the patio (relatively weak powerwasher mind) and noticed those black and white algae marks on the patio. I then used Mosgo Algae remover in a 1:5 ratio with water and while the algae seems to have lightened a small amount, it's not near what I would consider satisfactory considering the effort and how toxic the liquid is. Pictures 1 and 2 show before and after applying for 3 days in good weather.

Any advice or other solutions that might actually clear it up?

Thanks

Algae before (Medium).jpg

Algae after (Medium).jpg

irishbuzz

I think that's likely lichen rather than moss. You need to be careful with natural stone and what chemicals you use on it. A cleaner like this is suitable for stone paving: https://www.mcmonaglestone.com/protectit-surface-reviver

Alun

Yes, it's a lichen, and it gets really deep into the sandstone, not just on the surface. That's why it's so difficult to remove.

BurntAsh

Ah so it is lichen. I'll give the protectit a go and see how I get on. Thanks!