A word of warning re pressure washing some surfaces.
Approx 1988. In old home laid patio with the rather expensive golden Cotswold slabs... that looked like natural riven stone but were concrete...at vast expense. They looked super.
Over time they turned black with dirt/algae...so I pressure washed them. Messy job but very satisfying. Trouble was I removed the top surface, exposed the aggregate below which was porous, they then got black and horrid really quickly.
We ended up removing the whole area and put down genuine golden flint pebbles...looked super especially after rain.
Try one of the non-bleach containing products like Wet and Forget, Algon or Patio Magic. Be patient and give them time to work. It'll be two or three days before you see a difference and the appearance will continue to improve over the next few weeks. I use a 5 litre sprayer with a lance - makes it easy!
I've not used the Karcher cleaner, but as I mentioned earlier I do use Patio Magic which does remove lichen - it takes a few weeks after one spraying, but lichen does disappear over the following few weeks. Firstly it turns orange, then rain washes it away. It really does work well
Billericay - Essex
Knowledge is knowing that a tomato is a fruit. Wisdom is not putting it in a fruit salad.
The problem is that if you use vinegar of soda crystals you are still poisoning the soil and killing beneficial organisms. A specialist product will have enzymatic cleaners that will not leave any harmful residue behind them. And that's something worth paying for.
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works for ours and we’re in damp all the time.
Approx 1988. In old home laid patio with the rather expensive golden Cotswold slabs... that looked like natural riven stone but were concrete...at vast expense. They looked super.
Over time they turned black with dirt/algae...so I pressure washed them.
Messy job but very satisfying.
Trouble was I removed the top surface, exposed the aggregate below which was porous, they then got black and horrid really quickly.
We ended up removing the whole area and put down genuine golden flint pebbles...looked super especially after rain.
https://www.google.com/search?q=golden+flint+stones&tbm=isch&ved=2ahUKEwig-NmnqO31AhUNlf0HHQnmAtsQ2-cCegQIABAA&oq=golden+flint+stones&gs_lcp=CgNpbWcQARgAMgUIABCABDIECAAQGDoGCAAQBxAeOggIABAIEAcQHlCAB1ihJmDGOmgAcAB4AYABxAKIAdIMkgEHOC41LjAuMZgBAKABAaoBC2d3cy13aXotaW1nwAEB&sclient=img&ei=NOsAYqCOMY2q9u8PicyL2A0&bih=595&biw=1280&client=firefox-b-d#imgrc=CwOzDmYA070MsM
Don't call it dirt, call it " patination "
It really does work well
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
I think the last time I looked the latter was about 50p a bag!
https://www.youtube.com/watch?v=I982HgsbZzE
I live in west central Scotland - not where that photo is...