I have spent a year plus seeking out products to get moss/algae from growing onto rooftops. I have come up with some not so environmental products such as bleach. Then i have come across zinc sulphate. I have a few questions to ask to start off. Does zinc sulphate kill algae/moss or does it just control it from growing? in other words if you have have the moss growing already you need to deal with the moss first and then spray? Are there any other products that I could mix with zinc sulphate that will not provide a dangerous chemical reaction that will work in killing the algae/moss and will also control it? More of a question for a chemist i would suppose. Is all zinc sulphate the same? I see it sold from all over the world with difference percentage mixes. Is most zinc sulphate sold at the same percentage of zinc? Is zinc sulphate entirely safe to use? Sorry for all the questions. I really am trying to find a product that works for the line of work i am into. Thanks in advance.
Your question would better be posted in one of the plant subforums, as this one deals with fungi and lichenized fungi, and algae and moss are plants. I don't know the answer to your questions, but if you can find out what species of moss you are dealing with, you might be able to find out the ph it prefers, more acidic or more base, and so there may be some low or non toxic options for changing the ph of the moss's environment to something the moss can't handle. I've no idea whether algae could be sorted out similarly...interesting question... cheers, frog
I can't deal with your question about how to kill moss and algae on your roof; I just let mine grow, since it disguises the rather garish colour of my roof tiles. Besides which, mossy tiles are kind of a theme here. However, I can give you some help with zinc sulfate and percentages. Zinc sulfate, in and of itself, will always have the same amount of zinc in it (ie one part of zinc for every one part of sulfate.) It gets interesting when people start selling the adulterated forms that are available as herbicides. The "Percent" that you see is a percentage of zinc sulfate relative to whatever filler the company is selling. Thus, 10% ZnSO4 is weaker than 20% ZnSO4, and both are stronger than 5% ZnSO4. The higher concentrations can be diluted, but it's difficult to concentrate the weaker ones. I'd do a bit of research before dousing your whole roof. It will kill grass and most other organic matter as well; I'd reccomend grabbing a chunk of moss off your roof and doing some tests in your kitchen, to figure out the lowest possible concentration of ZnSO4 that will kill the moss. Do the same for the algae. And, just to find out, test a little pot of your grass to see what concentration will kill that. Iron sulfate is apparently also effective, but again, it will kill your grass. So will Bleach, Vinegar, or pretty much any other method of moss or algae removal. Personally, as I said earlier, I leave it be. I use bleach inside the house if the algae starts to trail, but that's pretty rare, since there's a house snail here (Ecuador) that eats the algae off my roof and tends to keep it under control. I like the moss, too, since it dampens the sound of the rain. However, a quick web search for algae killers turns up something from a brand that I've used in the past, with no ill results to anything. Safer's Moss & Algae Killer is probably worth checking out before you do anything too drastic. It's an organic solution; I used their insecticidal soaps almost exclusively for pest control when I lived in Canada. Frog: Would something that kills a Lichen also kill Algae? Interesting to ponder....
I participated in a lichen air pollution monitoring project once, and although many (most?) lichens seem to prefer clean air, a few appear to like air pollution; living on trees at busy streets. Would that also be expressible as a ph preference? The algae population blooms in fresh and salt waters I've seen mentioned in the news recently seem to be responding to the influx of large quantities of nitrogen, as the by-product of various human activities particularly farming. I'm not sure what sort of enviro change would be unfriendly to algae. I'm betting it's really going to depend on knowing the preferences of the specific kind (clade, species etc) of algae or lichen, or moss, as to whether one product or environmental change would potentially affect all three groups. whee! frog
For those who want to encourage moss, one treatment I've heard of is to mix a cowpat with some agar (jelling agent), and spray over the surface you want the moss to grow on. The cowpat provides the fertiliser, the agar helps it stick.
GO GREEN Pressure wash the roof at 750-1000 psi starting from the top down, making sure that all dirt is removed, the roof will lock like new again and for five years you won’t have no more moss. For the moss to start it need a medium, and that is the built-up of dirt on the edges of the overlapping singles and roof tile, from Dust, Pollen and Leaves. The moss will never start on a new roof because it is clean.
Incorporate a strip of zinc metal just below the peak of the roof & maybe one halfway down. The slowly oxidizing zinc should keep moss and lichen from growing below it on the roof. As for the low pressure washing.....good way to take years off a asphalt shingle roof.
Low pressure washing removes only what is already loos. My roof is 17 years old, I have pressure wash it twice and it is still in good condition.
