loamland

The roofs we have used it own, we did not scrub. We sprayed the roofs off after about a 40 minute dwell time using about 200psi. These were not extremely bad roofs, but they did have a good bit of algae on them. Not sure how well it will work on a more severe problem but will be finding out soon. We were using a pure sodium percarbonate formula. Our mix was 3/4 cup/ gallon of water. Gave good results on the roofs we tried it on.

I was also interested in the oxygen based products. I have tried them and they do work. Most work best when mixed using warm water and once mixed they have a limited life of about 6 hours. I have used them on asphalt roofs and also on vinyl siding. On really dirty surfaces they foam up like household hydrogen peroxide does. My results have been good. It's alot slower process on asphalt roofs but on siding it really works quick. The great thing is the products break down to hydrogen gas, oxygen and water. No chemical runoff at all. Great enviromental product.