On Sunday, November 8, 2020 at 9:39:31 AM UTC, RobH wrote:
On 06/11/2020 20:59, F wrote:
We've got a patio made up of light coloured concrete paving slabs with a
slightly rough texture. I've used a Karcher power washer to remove the
compost that the resident gardener has managed to tread into them but
there's a green stain (algae?) that's pretty resistant to removal.

Anyone got any suggestions on what might shift it?



I use diluted bleach in a large watering can to clean my patio, and have
done so for years. It's as clean now as it was just after it was first laid.

Moss on tarmac drive was ou problem but sprinkling it with biological washing powder (Aldi's cheapest) wiped it out. Good for a few year