I have been using Corte Clean for about 5 years. I put bird feeders on my deck over winter as well as plants in the summer. There is always a lot of residue from the birds, the seeds and the plants that stain the deck. I apply Corte Clean in the Spring and it takes about two hours because I use two bags and follow directions closely. My deck always looks like new after the treatment. I highly recommend Corte Clean and recommend it to all my friends and acquaintances who have composite decks.