How do you clean the black algae that forms on concrete, siding,decks?

Answer 1

Best Answer - Chosen by Voters

or use a power washer

Answer 2

Mix a little clorox in hot soapy water and sweep down the surfaces. The soap cleans it and the clorox kills the algae.

Answer 3

Mix clorox with water n a pump sprayer or spraybottle, and fully cover surafces affected. Let sit for a bit, then rinse. The bleach kills the algae and is diluted by the water so should not 'bleach' out anything you don't want it to.

Source(s):

Use the same method prior to pressure washing my house. It statrs to lossen and remove mildew and mold, and has never harmed anyhting.