Lindemann DEFY Roof Cleaner Concentrate- 1 Gallon

Easy to use and did remove some of the roof stains from algae. Didn't get tough stains off though and may have needed multiple applications.

This worked great for me! But you must use a pump sprayer to apply it, which typically means getting on the roof (to be avoided if at all possible). You can't use a hose-end sprayer because this product requires one gallon of solution to 6 gallons of water (6 to 1 ratio) and there are no hose-end sprays that can add that much solution to the spray.It would be best to first try putting a latter up to your gutter and use a product with a hose-end applicator, such as Wet and Forget or Spray and Forget. This approach is simpler, much safer, and really not expensive to try.I need to add that this product worked so well for me that I did spend hours searching for a hose-end applicator that would do the job, but nothing.

See for yourself at the ARMA bulletin-which also warns not to allow their roofing to be pressure washed!Paste the below link into your address bar and read from the manufacturers and ARMA yourself.[...]I am a professional "Florida Certified" roof cleaner. In business here in SW Florida since 1989. So, i'm not just spouting off, without knowledge. These products are an attempt to play on the "Environmentally Friendly" desire we all have! Chlorine is at least something we are familiar with. We drink it in our city water, wash our clothes in it and swim in it in our pools. Try that with these new unknown chemicals and you may grow a 3rd eye! LOL!On top of that, I have tested all the similar products that have come onto the market in the last few years [but not this one yet] and most all require either pressure washing [which they will tell you the pressure is turned way dow-that just makes it necessary to get the gun tip closer to your fragile shingle granules! Or, they tell you it will come clean in a few months or so-but want the $$$ NOW! The fact is, without pressure washing, none of them have worked in any of my tests. I believe they are all $$$ making gimmicks.They don't mention, that chlorine is made from common salt and when it dries, turns back into common salt. What does this become when dry?Who cares? Why not simply listen to the roofing manufacturers-like you do your cars manufacturer, etc?