I have a Trex deck located in New Jersey, which I have previously Corte Cleaned of mold, approximately 2 years ago. Corte Clean worked! Our deck looked like new. Last year we didn’t use Corte Clean, but only power washed. The mold got worse & worse as it took over the entire deck. We had some left-over Corte Clean with a “Best If Used By:” date that was in 2016. We tried using this product, and the mold stains did not come out, wasting our time and effort. I ordered fresh Corte Clean and called the company. So, I did the entire deck over. The deck wasn’t installed properly, with proper gapping. Water pools on the deck. It doesn’t drain properly. You can see how close the boards are in my pictures. That's a real problem. I had to blow the water off the deck. The only problem was that I was still working on the deck after the sun went down. So, in the morning there were a few water stains because it stayed wet overnight without the sun. Wow! A big difference. The fresh Corte Clean worked! I am very pleased. Finally got rid of all the dirt in between the slats. The mold stains are gone. I can live with the way the deck looks now and will proactively use Corte Clean so I spend less time and money.