Assume you are talking about a wood, not plastic-composite deck. I
would pressure wash and let sit for several days to dry out. Sanding
is drastic and reduces the amount of wood flooring and thus the
strength of the floor. Maybe one time is ok, but not repeatedly.
If I am able to clean it up real good with sanding, I am going to try
oil based stain. (This is pressure-treated wood but is at least 20
years old.) My experience with latex "stains" is that they act just
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