Quote Originally Posted by reggie747 View Post
Try sodium hypochlorite, works wonders.
Just used up 4 ltrs on my monoblock driveway - it's now about £33 per 4ltrs.

Dilute from 14% by vol to around 10% for use, and make sure if spraying it, that you clean off the pump - as it corrodes metals.

Don't get any on your clothes - it bleaches where it touches.