For the first time, I cleaned a house, ( Mine) I honestly don't know how you guys do it and I take my hat off to you but, watch out for the glare LoL! ( I'm bald as a babies rump) I had the same problem... We had black streaks from the gutters. After washing down the roof, The gutters just killed everything, The roof looked new again and I was happy about that but my gutters looked horrible. I went out to my service vehicle and grabbed my bottle of Super Clean and mixed it with water. ( about 1/2 gallon to 4 1/2 gallons of water). I foamed it with my foamer because I'm to lazy to use a squirt bottle. I treated the entire gutter and started from the other end. ( the side I foamed 1st.) Worked like a charm for me. Now my mix is a little different than I said above. When I buy say 5 gallons. I put 2 1/2 gallons into another container and top it with water. Now I have 10 gallons. Then from that bottle I pour 1/2 gallon to the 4 1/2 gallons of water. I was able to go around the house and still had enough to go around again.
Cleaning homes is not what I think I'd want to do. From now on, I'll hire someone else. I'll stick to those Yummy Hoods!