I have green/black algae growing on the cement from where the night condensation drips from the roof. Also where the concrete drive has water on it too many times it grows. Can anyone suggest a product to remove it. Preferably a product you spray on and wash off. Less work the better 555. I am up in Surin Isaan area so any ideas would be greatly appreciated. Thank you in advance

I have the same problem so any help would be appreciated. Was thinking of poring some bleach with acid but if someone has a better and practical idea I would be grateful, as I am not known for my gardening or DIY skills.

A power sprayer works for me.

power washer (100 bar) and after that you treat it with a product they sell in homepro to make it waterproof. It works very well, comes in tanks from 5 litre but also smaller. Just brush it on the cement and let it dry....make sure the cement is dry so it sucks well, repeat brushing if it sucks in very quick.

26 minutes ago, Laughing Gravy said:

Was thinking of poring some bleach with acid but if someone has a better and practical idea I would be grateful, as I am not known for my gardening or DIY skills.

 

Please do not mix bleach and acid. This combination can produce chlorine gas.

As mentioned above, buy a cheap pressure washer, works great and easy to do.

16 minutes ago, blackcab said:

 

Please do not mix bleach and acid. This combination can produce chlorine gas.

It was tongue in cheek saying that due to my poor skills but I appreciate the concern.

There is a product that has bleach and 13% HCL if I remember. It was that what I was referring too. The mold makes it very slippy and dangerous.

In the process of doing it myself.

Copper brush and water the old fashioned way.

Easy way get a pressure washer like in the car wash, blasts it all away.

Pressure washer , taking care tp splatter a little bleach around on the concrete. You'll be Ok until the next rainy season.

I have read that carbonised rice husks does a good job too, but I never tried it.

 

What about on areas that are painted? A pressure hose can remove the paint, likewise scrubbing with a wire brush. 

Cooked has posted the best solution....Use Chlorine granuals (pool chlorine), sprinkle it on the area and rub it in with a broom. Leave about 10 mins and then pressure wash the area. It wont be slippery and lasts for months. If you have grass around the edges DONT let the chlorine get on it or it will kill it completely.

Good luck.

12 minutes ago, Dexlowe said:

What about on areas that are painted? A pressure hose can remove the paint, likewise scrubbing with a wire brush. 

You wont need to pressure wash, if you use Chlorine, just hose it off with a normal hose pressure...BUT protect the grass , if you have any near the cement....

Cheers, weegee. 

38 minutes ago, weegee said:

Use Chlorine granuals (pool chlorine)

Do you know if places like Thai Watsadu sell this or only pool outlets? (Pattaya area)

 

if its only a small area spray it with a diluted mix of anti bacterial disinfectant and scrub it  then blast off with high pressure, this will kill off any of the fungal properties. 

18 minutes ago, Anythingleft? said:

Do you know if places like Thai Watsadu sell this or only pool outlets? (Pattaya area)

 

Use bleach

 

1 hour ago, Dexlowe said:

What about on areas that are painted? A pressure hose can remove the paint, likewise scrubbing with a wire brush. 

This is just one of the reasons why I don't paint concrete. You can mix a pigment into the concrete as you are mixing it but painting is a waste of time.

47 minutes ago, cooked said:

Use bleach

 

yep....but get a real strong one hey....I prefer the Chlorine as I get nearly 12 months mold free...

You can buy it most big stores if you ask, or to be sure it's strong, go to a pool shop...

BTW...I have found that snakes DONT like going places where i have done with a chlorine wash.

Regular bleach solution is ok, leave it to soak a while, then rinse

1 hour ago, cooked said:

This is just one of the reasons why I don't paint concrete. You can mix a pigment into the concrete as you are mixing it but painting is a waste of time.

 

Sadly, already painted when I moved in (and it didn't cross my mind). I had intended to cover all with brick fascia tiles, but given the massive property bubble in the Nong Prue area (Pattaya etc), it would be throwing good money after bad.

I have tried most of the stuff they sell at the big hardware stores here as far as what you pour on and let soak, spent a lot of money but haven't had any luck at all. Also tried bleach and bathroom cleaner (not together!). The only thing I have found to work was the pressure washer. I am going to give the chlorine idea a try though.

Don't use bottle bleach, use Oxy crystals and make sure none of it gets on the grass or plants.

I'm not seeing why granular chlorine would be effective if it is not dissolved? if you put granular crystals on then wash them away! can't see the sense in it.

 

We have some quite large areas that need to be cleaned annually, the best method I have found is to power wash, then scrub with a 50/50 bleach solution, do this on a evening and leave to work and dry overnight, if you do it in the sun the bleach gets burnt away quickly, why rinse it away, you've paid for it, let it do its work, the residue will burn off the following day.

 

Also, if paint is correctly applied, power washing it will not take it off, it should just clean it, if its washing off its a rubbish paint job!

A stiff brush and a lot of water, hard work !

 

I don't have a pressure washer.

 

Then spray the area with vinegar, this kills the mould spores remaining in the concrete.

If a power washer can't take paint off, it's a rubbish power washer.

1 hour ago, CGW said:

I'm not seeing why granular chlorine would be effective if it is not dissolved? if you put granular crystals on then wash them away! can't see the sense in it.

 

We have some quite large areas that need to be cleaned annually, the best method I have found is to power wash, then scrub with a 50/50 bleach solution, do this on a evening and leave to work and dry overnight, if you do it in the sun the bleach gets burnt away quickly, why rinse it away, you've paid for it, let it do its work, the residue will burn off the following day.

 

Also, if paint is correctly applied, power washing it will not take it off, it should just clean it, if its washing off its a rubbish paint job!

 

Wet the ground to be cleaned, mix the Oxy with water to the correct strength, spray on and leave for fifteen minutes, then power wash off.

 

Here's the mechanics of it all:  http://www.home-ec101.com/oxygen-bleach-an-introduction/

You've lost me! the article is about H2O2, which is not granulated chlorine, I'm sure H2O2 would do a good job if it was readily available in a 35% mix at a reasonable price, but at the end of the day I just want to clean mold!

17 minutes ago, CGW said:

You've lost me! the article is about H2O2, which is not granulated chlorine, I'm sure H2O2 would do a good job if it was readily available in a 35% mix at a reasonable price, but at the end of the day I just want to clean mold!

 

I didn't say granulated chlorine, I said Oxy crystals which are widely available here, mix it to whatever strength you wish but it doesn't take much at all - note from the link that one of its primary purposes is to eliminate mold and mildew.

1 hour ago, bankruatsteve said:

If a power washer can't take paint off, it's a rubbish power washer.

You learn something new everyday! I thought after a lifetime working with coatings and surface preparation I knew what I was talking about!

1 hour ago, chiang mai said:

 

I didn't say granulated chlorine, I said Oxy crystals which are widely available here, mix it to whatever strength you wish but it doesn't take much at all - note from the link that one of its primary purposes is to eliminate mold and mildew.

Sorry I thought you were replying as to why granulated chlorine was so effective!

3 hours ago, CGW said:

You learn something new everyday! I thought after a lifetime working with coatings and surface preparation I knew what I was talking about!

 

No disrespect intended.  Just saying power washers can be brutal to anything esp. on concrete surface.  Or, maybe you have never tested for that?