Moss and Mold

[BrettGC]

1 hour ago, GeoffH said:

Are you sure it’s moss?  It could be green mold?  Not sure what kills moss…

I'm pretty sure it is mate, it's hard to see in this photo but it does have some height.

[BrettGC]

18 minutes ago, Kingpin said:

Bleach kills everything, including moss.

The problem is that it will eventually return, especially with all this rainy weather.

I'll give it a shot, with Geoff's idea of detergent mixed in.  I have a 10ltr hand air pressure sprayer so I'll mix up a concoction in that. 

[Tommy T.]

My experience with mold/moss/mildew is similar to what was stated above... Bleach kills many things. Muriatic acid is a real scorcher for this stuff, but is a bit trickier to handle. A pressure washer really does the best with no environmental side effects. It needs to be done, preferably when the green stuff starts to appear, not when it establishes itself and on a regular basis - like every month or two if it is rainy/overcast. Or, maybe you can hire a kid to get down on hands and knees with a scrub brush and the bleach and detergent...

[GeoffH]

1 hour ago, BrettGC said:

I'm pretty sure it is mate, it's hard to see in this photo but it does have some height.

Yes that looks like moss not green mold.

[Gator]

In Florida had similar issues, though more with black and green mold as well as occasionally moss. At my shop I had a “Hotsy” brand hot water pressure washer (now called the “Hotsy 700”) that lasted me over 15 years without any issues. For the house I had a Karcher  brand gas powered one (don’t recall the model, but it was about 3,200 psi). It also lasted about 9 years before I sold it when I sold my house.
 

Hotsy pressure washers are quite expensive and would likely be overkill for non commercial use (I had it for cleaning my semi trucks, trailers and the shop floor). But I believe Karcher pressure washers are available here. Personally I’d recommend a gas powered one as the electric ones don’t seem last as long and most of them only get up to about 2,000 psi.  
 

For the cleaning solution on the sidewalks, driveways and buildings, I used 1 part TSP mixed with 3-4 parts warm water (dissolves easier) and 0.5 parts bleach. Once clean it it would be a few months before the mold would start to creep back along the edges of the sidewalks, driveway and bottom edges of my house and shop. 

Edited February 2, 2023 by Gator

[Tommy T.]

Good advice from @Gator! I might add that for moss, iron kills it quickly and effectively. When living near Seattle, moss was always an issue in the lawn. So I used an iron rich fertilizer that both nourished the grass but also killed the moss. I don't know if that could be applied to moss growing on concrete, though?

Edit:

I will add that TSP is considered a very nasty chemical, especially for the environment. Sorry to mention that, Gator, but that is my understanding. Of course, I have used it and may still use it, but I am not happy to affect the environment adversely.

 

 

Edited February 2, 2023 by Tommy T.

[Old55]

We get moss on our cement patio during winter. I spray vinegar like Brett called out. I use the 30% strong vinegar consenteate from the big box store for best results. 

[Tommy T.]

28 minutes ago, Old55 said:

We get moss on our cement patio during winter. I spray vinegar like Brett called out. I use the 30% strong vinegar consenteate from the big box store for best results. 

But....does it work?

You might get similar results using muriatic acid diluted? Just a question...

Edited February 2, 2023 by Tommy T.

[OnMyWay]

3 hours ago, BrettGC said:

 

What brand did you guys buy? So I know not to buy one in the event I change my mind 

Actually I'm happy with my PW.  It is a Diamond brand with a Honda 4 stroke engine and after 6 years it needs a good professional cleanup and tune.  I did it myself once a few years ago but I think I will have a "pro" do it this time.  It is only 2800 psi and I think the pump is getting old too, so a bit less pressure.

I don't recommend the small electric ones if you have anything large to do.  If you get a gas one try to get at least 3200 psi, and for driveways, get a surface cleaner attachment.  I have one something like this and my PW is too weak to run it properly.

https://www.amazon.com/Tool-Daily-Attachment-Extension-Replacement/dp/B08QHXR8RJ/ref=sr_1_4?keywords=power+washer+surface+cleaner&qid=1675304323&sr=8-4

After you get your new 3200 PSI PW, you will be hooked, and probably want to clean the whole neighborhood.

Check HMR.  They have some new ones sometimes.

[Old55]

1 hour ago, Tommy T. said:

But....does it work?

You might get similar results using muriatic acid diluted? Just a question...

Good question. The diluted muriatic acid could be best I have no way of knowing.