"wanderer" wrote in message
...

"Andy" wrote in message
...

"ben" wrote in message
...
A load of black circles about the size of a penny have appeared all
over
my concrete garden path, obviously some kind of mould or fungus or
something.

snip

You could try a strong solution of Caustic soda or power jet wash if you
have one but I don't think you have otherwise you would have used it.

Pressure wash is unlikely to work on these spots. I have a few on some of
the slabs around my pool, and whilst an annual spring pressure wash will
remove most of the accumulated dirt and crap from the slabs, it doesn't
touch these spots. As Ben says, you're left with slabs that are nice and
clean with the spots standing out even more.



Yours can't be doing it's job then A 100 psi can take paint of window sills,
My backyard was covered in all sort of dirt, moss, oil stains fungi, when I
had finished the concrete was gleaming.

Andy