Once I learned how to use Corte*Clean I found it to be very effective. It's important to clean the surface dirt off the day before using a water hose and deck brush. At first I had trouble getting all of the Corte*Clean to dissolve, and it would clog the sprayer. Also, I live in a breezy area where the spray would often blow back into my face. Being very sensitive to chemicals, this didn't work for me, so last year I tried applying the solution with a clean mop dedicated exclusively to Corte*Clean. This worked very well, and I plan to continue using this method.