Try brushing one of the spots with neat Jeyes Fluid and I think you will
have some success.

Regards,
Emrys Davies.


"Tumbleweed" wrote in
message ...
In particular, its a pernicious black type that grows in 'spots' that
resist
all but the most determined powerwashing, in fact the concrete goes at
the
same time. Power washer, bleach,and jeyes fluid are all proving no
match.
Any suggestions? Are there algae cleaners you can buy that are any
better?

--
Tumbleweed

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