Black Algae on Concrete
 

What is the best way to remove this and is there a way to prevent it ?

Buy 30 second outdoor cleaner at HD or Lowes, hose attachment sprayer. Leave on for at least 10 minutes to work in shade, rinse. Twice a year maintenance.

Yes, that works and I've done it with good results. Up north my concrete patio was very black on that concrete I used "Wet and Forget" it's about $35 for a small container, it doesn't work overnight but give it a few months and it will clean up the mess.

Yes, I have used wet and forget but 30 second is faster and significantly cheaper. There is a video on YouTube comparing outdoor algae cleaners and 30 second is clear winner. However, leaving it on for 30 seconds doesn't make since, just my opinion. I also use it on my house once a year.

You may be able to seal the driveway, but i would look into where the moisture is coming from and can it be eliminated. If you decide to seal, be sure it is correctly cleaned prior to sealing, and if you are doing it yourself, I would use the water based sealer, WITH shark grip added so you do not end up with a very slippery surface when wet.

it is mainly in the back along the sprinkler line

I agree the 30 second is faster and I used it 2 weeks ago on our white garage screens and some on the driveway. Wet and Forget is really pricey no dout about it.

Powerwash

Have you looked into adjusting the pattern of the spray heads, easy to do.

30 second cleaner is basically bleach … you will discover that after you ruin your shirt and pants…
Go with Wet & Forget it’s a conservative approach and works great…. Can you readjust a sprinkler head to avoid future problems? I use Wet & Forget on the house every 3 years …

I set up a garden sprayer with a 3:1 water to bleach solution and spray the infected areas. The spores will die and mother nature will take it away when it rains avoid getting on your lawn and plants.

We have small black spots on our vinyl siding. The chlorine-based "House Wash" sold at Lowes does a great job on the green algae but does not touch the black dots. Power washing doesn't handle it very well unless you focus the blast directly on it for a few seconds. With the numerous black spots scattered all over the house, this is not an effective way to treat the spots. Besides, the pressure washer damages the surface of the vinyl when used in that fashion.

My questions are: (1) does "30 Seconds" damage the vinyl surface? and (2) has anyone used "30 Seconds" on vinyl and was it effective?

Spray with White Ox and rinse off with hose.

A. Pressure Wash (Get an inexpensive unit like Sun Joe at Lowes).
B. No. ( Mold and Mildew vie for un-official Florida State Flower every day).

The black is probably just pollen that had fallen and decayed. That's what makes my driveway black, not algae. I find it easy to clean with an inexpensive pressure washer. I put some Simple Green in my soap tank, spray the driveway and then power wash it off. Takes a few minutes, but I save the money that I would have to pay someone else to do it. Some folks seal their driveway and say it makes it easier to clean.

Lanai Fabric Roll Down Screens
 

Anyone try the 30 second cleaner on the Fabric Roll Down Screens. They get mold and are very hard to clean. Mold Spots especially at night.

Distilled White Vinegar. It kills mold and prevents it from coming back. Bleach doesn't do that. Cleaning Concrete with Vinegar: 5 Things You Need to Know

30 Second outdoor cleaner is an excellent product. We hire a couple to clean the front and sides of our house, but we do the back ourselves because we don’t trust anyone else to not get cleaning products in our pool. We very carefully use 30 second on our pool deck, the birdcage screens, and vinyl siding on the back of the house. It works best if you first spray it on, wait a couple minutes, agitate it on the surface being cleaned, then thoroughly rinse it off. We use a stiff brush on the pool deck, a soft brush on the vinyl, and a big sponge on the birdcage screen. Takes about 2 1/2 hours for my wife and I to do the entire job once per year and it makes a big difference. Good luck with the project.

I personally just power washed the black stains off my driveway, but it took a long time, and it did damage my painted concrete.

Try attaching a round "surface cleaner" to your pressure washer. It reduces the pressure washing time significantly and cleans more uniformly than the tips.

I used a surface cleaner once a year because the stains and mold always came back.
Then I sealed it with this..
Amazon.com
No stains in three years.

Thanks, I'll try that.

Stain Defender question
 

Did it leave the concrete slick when wet? We worry about sealers that make wet concrete slippery.

Algae
 

I use a product called Wet and Forget. Hose end applicator, no scrubbing Works pretty well on my roof up north.

I was concerned about that too. But it's not slippery at all.
Although you can see it bead the water after three years.
btw, my 2 car plus GC driveway used 5 gallons total from a pump sprayer.

i prefer a bleach mix, however simple green also works and a pressure washer. Pretty easy. If you want to range out of the box then do an acid wash.

Either way once it's gone here's the keys of it

get rid of downspouts onto concrete
seal the concrete (2 coats)

that's all you have to do it won't come back if you do it the right way

Yes, I have. Just apply in the shade, not sun and rinse well. You can also use the wet and forget but not rinse.

Never use a pressure washer on plastics or vinyl. It will cause damage. Many outdoor items have a coating that offers protection from the elements, That coating is easily stripped off and then the surface is permanently wrecked.

I put myself on restriction using a power washer. Always costs me more to have things repaired after use.

When cleaning up, Dont forget YOUR CURB LINE IN THE STREET. :BigApplause:

You said it's used with a hose, but could I use it with my power washer?

No because the ratio of water would not be the same. It is sprayed on and left on, working slowly. No scrubbing or high power.

I would first try a power wash. Muriatic acid works well and is inexpensive-do not get on paint or plants..

I have black stains on my concrete. I like it. It gives a rustic look to my driveway.