Cleaning White Wall with Dashing

Ziycon

Over the years all the boundary walls have blackened and so have the capping bricks, is there a cheap way yo clean the dashed walls without taking off the dashing, I know a couple of stones will come off in the process!?

wait4me

Spray with a half and half mixture of bleach/water on a dry day; leave for an hour or two and (power)hose down.

CJhaughey

I tried bleach on algae and found that it comes back quickly once the bleach has evaporated.
The best product to remove and provide a longer lasting solution is Benzalkalonium Chloride, dilute with water and spray on with a garden sprayer.
This will kill the algae and prevent its reoccurence.

CherylHayes

There are Anti-Moss products that are environmentally friendly - You mix up a concentrated product with water and spray onto the wall and it will kill the moss and Algae and the root and prevent it coming back for around 12 months. If you only bleach it - it only discolours it and dosn't kill the root and it will get worse every time it comes back