A few weeks ago, our Company gave CorteClean Composite Cleaner a 5 star review. and said we'd be back-after using CorteClean on a deck "in much worse shape"... The Deck: TimberTech Composite Decking & Railing system-installed 2011*-in Cedar Embedded mold throughout. Extreme fading. Freakishly accelerated mildew growth. We thought this deck was minimum 10 years old-when we first saw it-in 2014. *Apparently 2011 was a very bad year for this product line-but so much worse for those who purchased....TimberTech refused our customers claim because she'd mentioned the word "mildew"... Time in: Deck Surface: 4 applications-approx. 3 hours including prep. Railing System*/multiple sections: approx. 1.5 *verticals are tough/but mold wasn't as prevalent as on the boards the Results: Nothing short of Amazing our customer was so happy-she cried! Synopsis: Whether you've neglected cleaning your composite deck, or were disappointed after using other products/methods, OR have a newer deck and want to keep it looking great, CorteClean Composite Cleaner really is the one-and only one- to use. Professional advise: if your gonna do it- Do it Right! Serious deck cleaning and maintenance isn't for everyone. If you don't own the proper equipment and/or aren't up to a couple/few hours working in the hot sun-hire someone to do it for you.