THE SMART TRICK OF ROOF CLEANING THAT NO ONE IS DISCUSSING

See pics two and 3. I am now getting ready to refinish the deck yet again this summertime. See Picture 4 of latest situation. The blotchy look has rather dissipated because of weathering from snow/rain (I are in northern Illinois). What did I do Improper previous yr? What would you propose I try this 12 months? Do I make use of the RAD stripper, cl