I actually used it in the past and it will clean. BUT, it is messy from the time you mix it to the time you have to rinse it. It leaves a white residue on anything it dries on, even when you think you rinsed really well. I actually used it quite a bit when I first started doing roofs 7 years ago. It's not totally water soluble, there is always a white powdery slop at the bottom of your tank that needs cleaned out somewhat regularly. So I started straining it through a vegetable strainer with a nylon stretched over it. But it still dried with a residue. But it did work. Although it does have a slower reaction time, it did work. I actually still "mess" with it here and there trying to figure out a way to use it. Do a search on these boards for "Calcium Hypochlorite".
Jeff