Moss, Mold, Mildew, & Algae Stain Remover Multi-Surface Outdoor Cleaner Concentrate, Original, 128 Fluid Ounces

This WnF is soooo great. A friend told me that the darkening of concrete over time is usually tiny black mold. WnF attacks that and brings your concrete bright again! Take before photos, apply, and then be patient. In 2-4 weeks you will see the result is bright white sidewalks and driveway, and very long-lasting. I regret pressure-washing my former driveway, as it removed small amounts of the surface; accelerating the concrete aging. However, WnF is not only easier, it lasts far longer than pressure-washing without removing parts of the surface. Because you need to wait weeks to see the result it is not as gratifying when applying. But know that it works; take before and after photos —or— test on one “square” of your sidewalk first. After a few weeks, that will be brighter than the adjacent squares. If you have green active growth on your stonework or shaded areas. You may notice it turn orange as the enzymes begin working. Any thick growth may later require removal, but WnF increases the length of time before growth returns. Usually several years in my experience. I use it on my concrete driveway, sidewalks, brick + mortar, and even the shaded side of my kids’ wooden playset roof. I used it on the padded portions of my boat trailer to make it look brand new, also. I am not an expert on what surfaces to avoid, but I avoid plants + grass and I allow to dry before my pets walk on it. Definitely purchase the concentrate and determine your own dilution. When I have tried the gardenhose-end variant of this WnF product, it appears less-effective. Always apply early morning or late evening so it can maximize before the sun evaporates. Also apply when you don’t think it will rain for 24 hours (turn off your sprinkler system for a day, if you have one). I hope that helps! I cannot say enough about how great this stuff works!

This stuff works! I love it! The mildew is gone after a few days!

I have been using this product for years. As long as you understand that it does not offer immediate results, you will not be disappointed. Yes, wet AND FORGET. Come back in a couple of weeks or so, and provided that it has been properly applied with time to dry (5 hrs) before a rainfall, and there have been some periods of modest rainfall in the days/weeks following the application (or you return to spray with clean water), the surface will be clear of green, black and other colorful mildew and algae growth. I have used this product on wood of all kinds (PT, painted or untreated), cement, masonry, aluminum and fiberglass surfaces, all with very good to excellent results. It has not harmed any of my extensive landscaping vegetation. I use it with a long-distance garden hose sprayer to cover my entire tile roof in FL, as I stand on a ladder at the edge of the roof. I have been doing this for years with great results. It can be expensive, but when you consider the labor involved with using alternative methods (pressure washing) I think it is worth every penny.

This cleaner does a decent job on newer outdoor stains — it lightens moss and mildew without harsh scrubbing, and I like that it’s gentle on surfaces. It’s easy to mix and apply, and the coverage goes a long way for decks, siding, or concrete. However, for older or deeply set stains, it’s not a miracle fix. You’ll likely need a scrub brush or some extra effort to get those areas truly clean. After using it a few times, I’d say it’s effective for maintenance and prevention, but not strong enough to replace a good scrub for long-standing buildup. A practical cleaner for regular upkeep — just don’t expect it to erase years of outdoor grime on its own. 🌧️🧽 — #1 Maryland Homeschool Oversight Program

Fantastic item. You have to already have the dispenser to hook up to your garden hose. This jug is a refill. When you spray it onto your sidewalk or driveway it goes on foamy. Don’t rinse it just let it absorb into the concrete. Every time it rains the concrete gets lighter. You could also use it prior to power washing.

Product works fantastic

I’ve used it three times of the last month and I’m not seeing any improvement. Very expensive too.

Expensive but it works well on concrete driveway surfaces in Florida that develop green and black mold during the course of each year. I used to pressure wash and then treat with this product, which provided a perfect white concrete result immediately. This year I tried it without the pressure wash. The way the product works is to kill the live mold and algae upon application, while penetrating and hanging on to the treated surface, and then washing clean as it (inevitably) rains. Surface mold and algae go from black / green to light brown / orange upon application, and then wash-out over period of weeks, providing a very acceptable outcome that lasts a year. I also use it on annually brick pool decks, wood trim, and painted stucco siding, which don't take well to pressure cleaning.