We have owned the lake home with an AZEK composite deck for 10 years in MN. The trees were dripping sap all over it. Nothing would remove it. I called Corte Clean customer service and they told me to use it at 2.5 scoops per gallon of water. I watched the YouTube Corte Clean video, which everyone should watch before using this product. It was absolutely wort the 6 minutes. I applied the Corte Clean, watched it bubble up and the sap stains disappear. I will be proactively using Corte Clean in the future. I couldn't be more thrilled! The product is simple and easy to use and the customer service is excellent! I will be recommending to my local hardware store and anyone whom owns a composite deck.