The temps are usually above 60 degrees. I'm not sure I have enough dawn in my solution. The run off is apparent. What about your mix and application process. We have lots of work out here and we are fairly new at roof cleaning. I know pressure is not good and would really like to be doing this properly. My roofs would be a mess if I didn't rinse them. On a typical 1500 square foot house we would use about 8-10 gallons of SH. Does that sound low? Let me know your thoughts. Thnks for the input. Bob G