When we bought Kelpue the cratch canopy ( black ) was pretty green and over the years since I have given them an occasional treatment of Wet and Forget which has not been entirely successful. This year we were given the tip of spraying on white vinegar the after a bit washing it off. This was more successful but as Iain rolled up the canopies as soon as we got to the boat, I have no idea what they are like now and I won't find out unless we get heavy rain and the canopies are put down. When they are rolled up, I just forget them 😀