We've got a patio made up of light coloured concrete paving slabs with a slightly rough texture. I've used a Karcher power washer to remove the compost that the resident gardener has managed to tread into them but there's a green stain (algae?) that's pretty resistant to removal.
Anyone got any suggestions on what might shift it?
Bac 50?
'Patio Magic' aka Benzalkonium chloride. It contains the same stuff as Alan recommended, but with a more pronounceable name, and is more dilute! Take your pick from e-bay suppliers here
+1; good stuff. Wilko and Robert Dyas sell it for something like £8.
Thanks. It sounds to need some fairly serious [protection when spraying it. How plant-safe is it?
Bac50 needs to be diluted 10:1 to 20:1 water:BAC50 for this application. Possibly not that plant friendly.
Sold on Ebay and elsewhere as easy to pronounce BAC50.
Green goes with bleach and heavy power washing. Its the black ones that are impossible to shift.
Does everyone *really* worry all that much about what colour their patio paving ends up as it weathers? Our patio paving (two areas outside sliding doors outside the house and one area round the pond) just get cleared of the weeds that pop up through the cracks and that's it. If they go funny colours with lichen or other such things then that's part of their attraction IMHO.
You don't clean all the funny patches off the bark of beech or silver birch trees (or do you).
That's how I feel about the 3cm deep moss on my outside concrete. Not everyone agrees with me though, especially the hedge sparrows which rip out great chunks of it looking for invertebrates.
Only when it's algae and wet, when the coeffcient of friction drops close to zero...
You don't normally walk on the lichen or algae on the bark of trees. Algae on paving slabs can be very slippery when wet.
We have black too. Forgot to mention that.
Thanks, all. It looks like an order for BAC50 will be going in.
If BAC50 shifts it, please let us know. I've tried everything
The problem is that this says its to treat moss. It says nothing about algae. I hope that it works But I fear it may not
In the first link I gave (random listing) it says
[quote] Used in fungicidal products to kill fungus, mould and algae. [/quote]I have personal experience of it effectively clearing a plastic roof of a thick film of green algae.
From
Good. Now will it clear black algae? I have no problem clearing green and red algae and moss with a pressure washer...
I use diluted bleach in a large watering can to clean my patio, and have done so for years. It's as clean now as it was just after it was first laid.
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