My decking is black and needs cleaning. Can anyone recommend anything strong apart from a pressure washer, which somebody suggested and which is not recommended because it opens up the wood and makes it crack?
I have used a pressure washer very successfully many times - set it on half width spray, and use at a very shallow angle. Scrub the decking first, along the grooves using a soft broom and a strong solution of washing up liquid or similar (resultant spray will also keep green- and blackfly at bay on nearby plants!). If very black try "Disclean" (concrete cleaner) or similar, diluted 5:1. (but mind the plants!!)