I powerwashed my deck two weeks ago and am planning on sealing it with Behr waterproofing wood finish, oil formula in a cedartone. I was hoping I didn't have to use a spray on cleaner beforehand. What would happen if I didn't?
Power washing generally does a pretty doggone good job of cleaning. As long as the deck appears to be clean, then nothing should happen.
As a side note, do a search for Behr products in the painting forum... you may change your product choice after reading some of the reviews. I've used Olympic Stains with great results. Other opinions my vary.