People are always asking my opinion of different fad roof cleaning products that they saw in the store or on the internet or wherever, and I always try to patiently explain that there is a safer, more effective way. Trust me that if there was a way to profitably package and sell a bleach-based roof cleaning solution to the public I believe these companies would do it because they should know it’s the safest and most effective method, but there isn’t so they don’t.
Instead they’ve developed these powdered or condensed products that they can manufacture cheaply, ship light for next to nothing, and let you deal with doing all the work (like mixing, renting a power washer, etc.). They go to great lengths to bash bleach/chlorine based solutions because it’s not something that they can profitably sell! They’ll tell you how “green” their product is and how “bad” bleach is but if you do your research (the fact that you’re here at this site is a good start) you’ll discover that bleach-based roof cleaning is the superior method from both a safety and effectiveness standpoint if you know what you’re doing. I’ve cleaned hundreds of roofs with bleach (and ZERO pressure, by the way) and an experienced rinse man, and we’ve never once seen roof, gutter, or house damage as a result.
On the other hand, I can tell you there’s a chance that if you try to use one of those fad products on your roof in conjunction with a pressure washing wand that you’ll lose significant numbers of granules from your shingles. I’ve seen it first hand where other roof cleaners have taken high pressure to a roof and there are literally hundreds if not thousands of shingle granules on the ground circling the entire perimeter of the house. This is not good! They might even tell you that they’ll use an extension piece to disperse the pressure through multiple nozzles and though this is a step in the right direction it’s still too much psi for my comfort level. Other purveyors of these kinds of products will tell you to spray it on a few times over the course of a few weeks without the aid of a pressure washer and you’ll see some results three months to a year down the road. Well, I guess if you’re willing to wait that long then be my guest.
As for me, I’ll stick with non-pressure and bleach, thank you very much. I suggest you do the same, or at least hire a professional non-pressure roof cleaning service to do it for you safely and effectively.
The Cincinnati roof cleaning market, like most in the Midwest and northern states, is still a relatively new one, as roof algae has only started to take hold there over the last decade or two, but it’s encouraging to see businesses like this one springing up that use the proper procedures instead of simply throwing the latest fad 
Usually the process begins when an algae spore lands on and attaches to your roof. It then begins to consume the limestone filler in your shingles’ granules. The limestone acts as a food source for the algae and allows it to grow and eventually cover larger and larger portions of your roof’s surface. So as the algae grows across your roof it is literally eating the shingles! If the growth goes unchecked it will eventually cause loss of roof granules, which are vital to the reflective properties of your roof. When these granules are lost it leads to greater heat build-up which leads to higher energy costs for you, especially on those hot summer days when the AC is blasting!
Imagine a potential buyer pulling into the driveway of an otherwise beautiful home, but the roof is covered in some kind of mystery “black stuff”. They’re going to think to themselves that the roof is sick and may even need replacing (although it just needs a cleaning). They’ll be adding up the cost of a new roof before they’ve even stepped foot in the house! How’s that for lousy curb appeal! Sellers can’t afford to be this careless with how the exterior of their home looks. That bad “first impression” that the potential buyer has will often times trump any upgrades or features that are inside the house. Roof stains and/or moss could also catch the attention of a home inspector who might decide to make negative comments about it to his clients, who in turn might offer less than they would otherwise.