Hi Guys n Girls long time no speak. Looking for some advice with some Casalgrande tiles we have supplied that are being used outside. They are very light (thassos colour) and are staining a lot. In the summer months bird sh*t was terrible to get off, now its the leaves leaving stained outlines. Any suggestions? Ive tried all sorts with some working and some not. Today it was Oxy-klenza from Dry-treat and normal household bleach, I've also used acids and other cleaners too.