My driveway gets horrible black slime in the rainy season as our house has no guttering.

I have a pressure hose but no patio-cleaning attachment (and can’t get one here) so cleaning the driveway is like colouring in a football pitch with a biro. The drive’s around 30m x 4m.

Someone’s told me chlorine will work. Will it?

Thanks

Bleach will certainly kill anything organic but putting that into the environment is no better than flinging engine oil or antifreeze down the drain. Would you not be better actually getting some guttering on though? I’m sure your house would thank you apart form anything else.

no better than flinging engine oil or antifreeze down the drain.

Not really in this case

The bleach will diluted by the water and breaks down fairly quickly.

The engine oil is much more persistent.

Any effective chemical cleaner will cause some damage to the environment.

I’d not be happy using chlorine or some of the quaternary ammonium compound based driveway cleaners due to their poor environmental credentials.

Something sodium percarbonate based in very hot water or some hydrogen peroxide would be my recommendation.

Have a look at http://www.pavingexpert.com/pavguide.htm

option 1 – install guttering

option 2 – buy driveway cleaning attachment.

How did you jump straight to chlorine?

It’s a rented house and with the torrential rain we get here (Thailand), most houses don’t have guttering as it simply couldn’t cope. We don’t get the light rain that guttering would be of use for. We had 80cm in an afternoon last week.

There are 20cm kerbstones going down the drive between the concrete surface and the lawn(s) so I’d be surprised if it got onto anything organic.

Is hydrogen peroxide expensive as I assume I’d need a good few litres.

Anna, your link confused me ???

I can’t find any kind of driveway cleaner over here, percarbonate or otherwise. It was someone in a hardware shop who told me to use chlorine when the closet chemical they had was removal of concrete from tiles.

I can’t buy the patio cleaning adapter here either. We’ll be home (UK) for Christmas but can’t wait until then. Parts of the driveway are like an ice-rink.

I you want percarbonate then buy a big tub of laundry destainer powder and use that in very hot water.

Not really in this case

The bleach will diluted by the water and breaks down fairly quickly.

http://www.sciencelab.com/msds.php?msdsId=9925000

MSDS says no.

And if that isn’t enough, our main coolant system gets dosed with it, 540l/h into 102648 tonnes per hour. Maybe it does break down but it’s potent stuff until it’s diluted.

OP – kerb stones will do nothing, presumably the water drains away yes?

We just use floor cleaner, very hot water and a stiff long handled brush.

Patio magic?

Hypochlorite does break down to salt quickly, on contact with organic matter. It should work on your path – just brush it in.

A stiff brush, some mild detergent with a bit of sand / grit thrown in for good measures would get rid of the slime pretty quick and would be a lot less harmful to the environment.

Mild detergent = ?? Clothes washing powder?

Is laundry destainer powder different to regular laundry powder. Something like vanish would be an expensive proposition.

So hypochlorite (bleach, as google tells me) should work too? Is that as bad for the environment as chlorine?

What floor cleaner do you mean ghostly? I tried ‘regular’ stuff, half the dilution it says and it did nothing.

If you used liquid chlorine you would almost certainly die, along with anyone nearby. Sodium Hypochlorite solution is just normal bleach. Yes it’s bad for the environment.

You just need to get rid of the slime-iness. Some sort of soap / detergent and a bit scrubbing will see it right.

If I remember right… Chlorine is a gas under normal conditions. What’s sold as chlorine solution is actually bleach / sodium hypochlorite. That’s an oxidising agent, which breaks down when in contact with organic matter & other stuff, to a brine solution.

makecoldplayhistory – I live on the edge of a rain forest in Thailand, wet season kicked in last week for us, first time in a couple of years it has been really wet.

Everything is smelling foosty, bloody scorpions keep venturing into the house as well. We live in a Bali style house, which basicaly means we have to go outside from our bedrooms to get anywhere, which is shit at 5am, when it is black, and pissing down with a tropical downpour, it was 20 degrees here yesterday morning, bloody freezing it was

You should be able to pick up a 5 gallon container of HCl at a pool shop, you are in Phuket aren’t you? Loads of pool shops there.

Why don’t you hire some day labourers for 300B a day and get them to scrub it for you. I know that is a bit pricey with the current sterling prices, but it is still a good price to get your drive way scrubbed clean.

Jeyes Fluid if you can get hold of it where you are.

This is all getting much more sciency than I expected!

Thanks for all the suggestions. I’ll try them all and they seem to be fairly easily ranked in order from safety for me and the environment up to (and including) almost certainly dying along with anyone else near by!

Yes Quirrel – Phuket. Day labourers are unreliable and generally can’t be arsed here. Much easier for them to make money taking yaba and fleecing driving tourists in a tuk tuk.

Where are you? Rainy season’s been in full flow for months here. Waiting for it to end.

Buy a big jar of herring rollmops from Lidl*, enjoy the fish and then use the vinegar to clean the drive. 😉

* Or elsewhere if Lidl aren’t in Thailand.

This reminds me of the time my brother drew a giant penis on the drive with a powerhose.

That’s all I’ve got to offer, sorry.

We just use a citrusy bleachy stuff, no idea what it’s called.
Should be one cap per gallon. I use it at one “big dollop” per bucket (about double strength) then scrub.
A big chunk of forest drains across our drive so we get a mixture of leaf mold, tree slime, mud, moss and dead greenery (leaves and grass trimmings).
Takes me an hour to do both sides of ours. Probably a bit smaller than yours. In the plus side it only needs doing every other year. And if I get the patio/decking cleaning thing on it early enough in the season I can put it off for another year…….

hypochlorite. That’s an oxidising agent, which breaks down when in contact with organic matter & other stuff, to a brine solution

No. It’s dissociates to sodium and a hydroxyl radical. this makes it a reducing agent, and a strong one at that.

Bicarbonate of soda is slightly alkaline.
Dilute it and let it do its magic on your drive.

Repeat this time with vinegar (the clear variety) a couple of weeks later.

OP having lived in Asia I know just the sort of black mold stuff that appears oh so quickly in the Tropics. TBH given cost of labour there I would have 1 or 2 guys just scrub it clean with stiff brushes even on hands and knees with a wire brushes. Surely you could hire a guy with a mobile pressure washer ?

Many years ago they used to use some sort of lime to clear the slimy seaweed off the slipway at the rowing club I was a member of.
It may have been quicklime and it’s probably been banned by now.

Copper sulphate was used for cleaning algae from slipways 🙂

I’d use chlorine/bromine, safe to use in drinking water it’ll be fine for driveways…