It's become quite common, in a Google search "North Port, Port Charlotte,and Punta Gorda, Florida Roof Cleaning" a few companies who are claiming to use green, environmentally friendly roof cleaning methods and chemicals lately!
It's the newest idea for a gimmick money maker!
As a 23 year professional roof cleaner, I hate seeing the public fooled by seeing Florida roof cleaning contractors promote themselves as using "safe" and green roof treatments when often, the chemicals are really treatments such as S hydroxide, copper napthenate, zinc napthenate and zinc chloride on Florida roofs. Heavy metal treatments etc? I do not see the environmentally friendly roof cleaning aspect of all this.
The only 100% Green method, known to me, is power washing the roof with no chemicals, just water. Now, that is being done. A roof will come clean "looking" just by blasting the algae off. The algae was not killed, so after pressure washing, the roof is still coated in living algae spores, [ so is your yard etc] ready to grow strong and black again in under a year. Of course, that pressure also takes years off the life of your roof and may well void your roof's warranty, but it is 100% environmentally friendly, at first glance. First glance? Yes, nothing will ruin a roof faster than pressure washing it, so if you you look at the long term picture, you are adding to the asphalt / tar / metals etc, in the landfills, as roofs need replacing at half life. That's not eco-friendly at all, just expensive for you!
Other than the chemicals I listed above, who knows what chemicals are used to make a new roof cleaning mix? Most are called "Proprietary" mixes, in other words, the ingredients are secret and you don't know what they are! We do know chlorine bleach though! We drink it in our faucet water, soak in it in our showers, do our laundry with it and swim in it in our pools. It is bio-degradable and after applying it to a roof, it reverts back to what it was made from-common salt.
I would be happy, as a roof cleaning contractor, to have an alternative cleaning chemical that works! I have tried these new things as they came out on the store shelves and not 1 gave even close to satisfactory results!All that I found were "Green Roof Cleaning" stories. Whenever a truly green, safe, environmentally friendly roof cleaning product is manufactured, that really works and will not void your roofing manufacturers warranty, I will start using it! But, I won't make believe they exist, before they do! Right now, they do not!