Mold or fungus staining concrete

Stan in Oly, WA

Well-known Member
The west facing concrete steps down to the sidewalk in front of my house are black from whatever grows on them during our long, cool rainy season (October to May). My wife and I scrubbed a lot of it off with a stiff brush and water, but in some places there are discolored spots that seem impervious to scrubbing, even with a bit of detergent added. Can anyone recommend a good concrete cleaner, preferably for this specific situation, but a general purpose concrete cleaner would be good to know about, too.

Thanks,

Stan
 

Try vinegar , sounds odd but it has logic to it . The vinegar actually feeds mold spores , it feeds them so much that they burst and die . Rinse the area lightly with a 1 part to 4 parts water mix two or three times over a week and leave to dry each time . Once this has been done wait a further week then scrub with salty water . Bleach is great for removing the stains left behind but wash with vinegar afterwards .
Absolutely guaranteed to get rid of the pesky stuff , works in the shower as well .
 
(quoted from post at 00:44:25 07/08/14)
Try vinegar , sounds odd but it has logic to it . The vinegar actually feeds mold spores , it feeds them so much that they burst and die . Rinse the area lightly with a 1 part to 4 parts water mix two or three times over a week and leave to dry each time . Once this has been done wait a further week then scrub with salty water . Bleach is great for removing the stains left behind but wash with vinegar afterwards .
Absolutely guaranteed to get rid of the pesky stuff , works in the shower as well .

I think they showed those spores bursting and dying on Myth Busters. Right?
 
I have had some blackish greenish stains on concrete and used a product called Wet It N Forget It. I just sprayed it on and in 3 weeks or so it was almost gone.
If you want it off right away it will not work, but if you can wait it works well. The instructions say if heavy staining may require two applications. One on only a few products i have found that actually does what it says. I have got mine at Walmart but have seen it at bit box and hardware stores.
 
I have had some blackish greenish stains on concrete and used a product called Wet It N Forget It. I just sprayed it on and in 3 weeks or so it was almost gone.
If you want it off right away it will not work, but if you can wait it works well. The instructions say if heavy staining may require two applications. One on only a few products i have found that actually does what it says. I have got mine at Walmart but have seen it at bit box and hardware stores.
 
I've never tried it on concrete, but 30 Seconds Outdoor Cleaner seems to work real well on mold and algae on wood and siding here in western WA. Don't see why it wouldn't work on concrete. It's pretty much just bleach, but I've found it works better than the generic bleach cleaners. Must have some detergents added.
 
(quoted from post at 12:26:30 07/08/14)
I think they showed those spores bursting and dying on Myth Busters. Right?

Don't know , we only get really old episodes of that programme here in Australia . That particular tip comes from a 1960's copy of the CWA handbook [ Country Women's Association ]. Don't ever call any of their tips into question or they will round you up with the sheep and shear you :lol:
 
Got access to a pressure washer? Here in the south, muratic acid is commonly used for cleaning concrete, bricks, blocks, etc...
Spray it on with a hand pump sprayer, let it set for a few minutes, pressure wash it off. Try a small area first to see how long you need to let it sit, but don't let it dry out. Muratic acid is an acid, so observe all the safty precautions. We get it at Lowe's and Home Depot.

Good luck with what ever you use.

Roger
 
Try plain ordinary household BLEACH (Sodium Hypochlorite), it will kill the mold/fungus & bleach out the concrete.

As for a concrete cleaner, the best that I've found is ZEP Alkaline Concrete Cleaner. It's bright Orange crystals, but when you dissolve them in water (I use HOT water) it turns a beautiful fluorescent Green. Wear rubber gloves & eye protection because this stuff is CAUSTIC.


Doc :>)
 
Charles in Aus.:

Are they still running Woolies down under ? I
thought that industry had pretty much died out.


Doc :>)
 
(quoted from post at 15:36:27 07/09/14) Charles in Aus.:
Are they still running Woolies down under ? I
thought that industry had pretty much died out.
Doc :>)

Still plenty here Doc , the product has changed a bit . Lots are exported live to Indonesia and the Middle East . Not much refrigeration there so live is the only real way . They don't treat them humanely and that is causing a lot of breeders to pull out of the market even though it is profitable .
Wool has changed its focus , many growers concentrate on superfine Merino . These fibres are what the Italians pay hundreds of thousands of dollars per bale for . Made into top end Men's suits for the likes of Bill Clinton and Rupert Murdoch I suppose . The poor sheep get about with little coats on them in case a grass seed gets stuck in their fleece .
 

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