Martin wrote:

How about all the water you waste? Cif removes algae.

Ho bum. Good point. Forgot about the water. Always do. Right. Elbow
grease then, a bucket, a good brush and hoping Sara's decking's not too
grand.

But not Cif. You perhaps would. I won't and never will. Methyl, propyl,
triclosan, diethyl phthalate , ethyl and butyl esters of
para-hydroxybenzoic acid not to mention 20 more chemicals in it is
frankly not a good idea. In my garden that is )