We have a concrete patio that gets rained on, but is in the shadow of our huge oak tree... so it drys slowly. There is also this blackish-greenish ting to the surface.
I would like to power wash it - which I do every so often, but then is there any suggested sealer to apply to help minimize to slime, and yet not make it a slick falling hazard when it rains ?
Lookng out the window - raining today - I guess the same is true of our front sidewalk and driveway :)
They make concrete pool deck paint. Google it.
I would spill a bit of bleach on that concrete patio and see if the blackish green tinge disappears in the area the bleach was spilled. If so, then it's just a bit of mold growing on the concrete probably because of the organic material falling from the tree (like aphid and other bug crap). The bleach will kill the mold, but I expect that it'll eventually come back if there's food dropping from the tree onto the concrete pad.
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