Patio slabs get very green and slippy

[purplemonkey]

Hi,

I laid our yard with grey stone slabs a couple of years ago. And last year I had to jet wash the slabs as they went all green and became very slippy.
The same thing has happened again this year.
It starts to go green toward the winter, I'm guessing the extra rain and lack of sun light.

Is there something I can do here to can having to jet wash them every year?

 

[stem]

There are products on the market that are very effective at getting rid of the green mould.

I use Patio Magic, which I just apply with a garden sprayer in the spring and after a couple of days, all the mould has gone without leaving a trace. I have also used it on my decking and fence panels too. The biggest problem I've had is finding a couple of consecutive dry days in April to apply it.

 

[purplemonkey]

So am I cursed with doing this or similar every year?

 

[stem]

Probably. Unless you put your slabs under cover every winter. Some winters seem to generate more mould than others.

It's much quicker than jet washing, only probably takes me half an hour to do the patio, decking and fence. Once done it then stays clear of mould all summer.

 

[purplemonkey]

Someone did mention sealing the slabs, could that make a difference?

I'll grab some patio magic and do them that way this time, see the difference. Jet washing was quite time consuming

 

[StephenOak]

My front yard is north facing and tarmac in a rather poor state, so it gets quite mossy.

I used Patio Magic a couple of times and it does work quite well, however it is not cheap. On Amazon currently £17 for 5L.

The active ingredient is benzalkonium chloride and in PM that is at 7.5%, you dilute it 4:1 taking down to 1.5% which will do 85m^2. That is for treating existing non-trivial moss. For prevention or v. light moss you can dilute it 9:1 (0.75%) when it will do 170m^2.

So I bought 5L of 50% benzalkonium chloride (from a chemical supplier via Amazon) five years ago and I am still using that. I paid £34 for that but I see it is available via Amazon for £26.

 

[scbk]

Try soda crystals, £1 a bag in Tesco etc