I have used the product before and it does work. It can take a month or two for the product to work as it takes time to clean a very dirty roof. Product tell you tat on the description. Go for it.

I used this stuff. I used the kind that attaches to hose. Although I did not have a moss issue, I had dark algae streaks on my roof and over time it did def improve the appearance of my roof so I did another round of it this year. All and all for the investment I was pretty happy with my results. Like I said I've done it twice. Once last year and just now again this year. For normal black algae roof stains it did fairly well. It's not a miracle worker but does well on light to moderate issues. It does take some time and patience and maybe a follow up. . If you have severe issues may need a professional or attack it with the zinc strips for alagae discoloration. I have a light roof and its not old enough to really warrant replacement yet, but asethically the dark streaks were not inviting and this product made me much happier with it until the time I want or need to replace my roof. My roof still has some years left in it so I'd like to make it last and this product def helped. That's my opinion. I would use it as an annual or every other year regular food maintenance item. All else, it's good to keep alagae growth down as it actually breaks shingles down over time so keeping it removed seems to be a good idea to me.

I used it on our deck, railing and roofing which was badly mildewed and had green algae on it. It's only been a few hours since I sprayed it and it's already 50% better.

Works wonderful for pavers around our pool and deck"¦I spray it on use a broom to brush it in then let it set"¦couple of days clean surface. Don't have to do anything for a couple of months"¦works to remove mold on wood around the house exterior as well.

We have a 21 year old gazebo. We thought we needed a new roof. We got several estimates, a couple of them said the roof was okay, just needed a cleaning. Sure enough, my husband attached the cleaner to the hose on a day where it was going to rain through the night. It's been a couple of weeks, we can see a big difference. Most of the green mold is gone, the wooden shingles are looking great! I think it worked really well, expecially for an older roof.