Mix to get rid of green algae on slabs?

Slabs, gravel boards and paving stones are going green.
I know diluted bleach in a spray bottle kills it but just wondering if I should add anything else. Sure someone once told me to add soda (presumably costic soda)
Thanks

 

Jet wash.

Andy

 

I try to avoid jet washing at all costs. Especially block pavers. This was also the advice from the company who laid our block paving.
They can take the top layer off and then more stuff starts to grow on it

 

see below:



Andy

 

Just because you can, it doesnt mean you should. When you get wash paving you they have to kiln all the joints again and potentially seal them all again. Its not just a case if jetwashing if you want to do it right.

Im not asking of ways to clean block paving, I'm asking for solution mix to use to kill algae.

 

Soda Crystals - Mix with hot water in a bucket, swill over the area and leave for 5-10mins or so then a scrub with a yard brush and rinse off. About a quid for 1kg packet, they have many other uses around the home too.

https://experthometips.com/soda-crystals

 

Does this work well? We get a lot of moss on our tarmac driveway every year several times, mainly because it is North-facing and Winter in this country brings 4 months of permanent damp.

The article says leave for an hour, you say leave for 10 mins.

 

Try Wet And Forget.

It seems to work.

You might still be able to find a source of Armillatox, which is now sold as a soapy cleanser.

 

On my north facing tarmac driveway I also get a lot of moss. I used Patio Magic and it worked well but isn't as cheap as soda.

The (main?) active ingredient in Patio Magic is benzalkonium chloride. Patio Magic 'concentrate' is, IIRC, 7.5% and you dilute it 4:1 (or 9:1 for light growth).

Because my driveway is in a poor state it needs doing every year, so I bought 5L of 50% benzalkonium chloride (5 years ago) which will last a long time and cost c. the same as two years of Patio Magic.

 

Moss no algae yes, I just wet it and start scrubbing straight away as the hotter the water is the better it seems to works, not sure how it works on tarmac I've only used it on my concrete drive but don't see that would make much difference. All it is is a very powerful soap, there's no real chemical reactions, it's like kryptonite to algae.

 

Thanks -- got the other half to pick some up from Wilko yesterday so will give it a go at the weekend. To be honest it's mostly algae.

 

It is also poisonous, not only to people who swig it, but also to animals in contact with treated surfaces.

I imagine cats who walk on it and lick their feet would be most at risk.

 

I have two cats so thank you for the heads up. There is no real mention of this on the packet other than general warnings over ingesting it.

I'll keep them in and once I've brushed it into the drive, I'll rinse away thoroughly into the drain.

 

You could class washing up liquid as poisonous to cats and dogs too I suppose, which I'm sure some people use to mop their floors with occasionally.

Also in an emergency where a pet dog or cat has obviously ingested something toxic and its life may be threatened and
you don't have access to a local vet, some vets advise you to induce vomiting by administering a small amount of fairy liquid (other brands are available) or a very small amount of soda crystals.

 

Since washing up liquid is designed to be used on eating and drinking vessels and utensils, I'm pretty sure it is not generally considered to be poisonous.

A chemical that is generally used as a biocide, however...