A lot of the other (non chlorine) mixes need to be rinsed off with some pressure applied or else they have to sit for a really long time before effectively killing off the mold. I myself have never used them but this is what I've heard. A lot of them are only trying to make money by using scare tactics and telling everyone that SH is no good for your roof which is a load of B.S. But, it works for some people. They're making loads of money by patenting and selling different mixtures of chemicals and scaring everyone into buying them. Don't believe the hype. Find a pool supply store that will sell you some 12.5% shock in bulk, throw in some TSP and Borax if you want and go to town. It's cheap, fast and very effective. And as long as you rinse, it won't cause damage to the shingles. Shingles are made to repel liquids so the SH isn't being absorbed by the shingles and it's only on there for between 15-30 minutes. It will however damage the landscape around the house so make sure you drown all plant life in water before spraying and also, be careful for wooden fences and decks because it will bleach the wood. Also, copper gutters can become tarnished and (obviously) be very careful on houses with natural wood siding because any overspray onto it will streak it. Basically, don't do it alone. I always bring someone with me (you don't have to pay them a lot) to rinse off the plants and house while I am on the roof. I don't let them on the roof. They only help load and unload equipment and rinse stuff off so I can justify not paying them a lot. Oh yea, one more thing is to run those big, black plastic irrigation hoses from the downspouts to the street so when you rinse the roof, you dont kill the lawn. Hope this helps.