That's funny. I heard from two clients this week who got advice from Lowe's that a power washer is the worst thing you could use on the deck and they never mentioned brightening/neutralizing the harsh chemicals they sold them. Needless to say, I was called cause things don't always go the way the big box stores tell you they will. The biggest piece of advice I have for do it yourselfers is to never use a solid color stain on their decking (its okay on verticals like spindles).