"Phil L" wrote in message
.uk...
Mike wrote:
:: Can anyone suggest a cheap method to clean up my paving ,ive
heard
:: a week mix of Bleach and water bring back the the " as new look "
:: The paving is only 3 years old ,hopefully I can catch it early .
:: I dont mind scrubbing ,but domestic power washers are a waste of
:: time. Thanks Mike .

You don't need any specailist stuff and if you do it correctly, you
don't
need to scrub neither!
Buy a tub of caustic soda and mix it according to the label, water
it evenly
over the paving, preferably when it's damp, to allow it to work
before
evaporating/drying up.
Leave it for 45 minutes.
Go over it again with a few watering cans of clean water and give it
a good
brushing with a stiff yard brush, this will partially rinse it and
remove
all the dead algy (which incidentally stinks to high heavens when
it's
killed)....any alkali will kill algy

I have seen algae grow on limestone

and it doesn't need to be particularly
strong - I found this out by accident when using sand/cement which
is a
fairly weak alkali, brushing up and washing down at the end of the
day
resulted in clean patches on the green paving stones where the mix
had been.

When you've give it all a good brushing over, rinse it down
thoroughly with
the hosepipe, you may need someone to help you here, to brush the
water into
the drain.

*** CAUTION***
Caustic soda will take your skin right off and is an irritant even
in it's
weakest solution.
It will bring cold water to the boil when mixed and may give off a
sharp
smell.
If you have any pets or kids they will need to be kept away, and
preferably
locked up:-p
you will need old clothing when using it as it acts like acid.
I don't know the toxicity of it WRT plant life but can't imagine
that it
will do them any good.
Only use this method if you are confident that little or none will
end up on
the soil - it's ok for patio's with drains to wash it into.

If, as you say, algae hate alkaline conditions, it should not be
necessary to go to such drastic measures as using caustic soda.
Scrubbing with a washing soda solution, or putting down a thick
dusting of garden lime and leaving it in situ for the rain to disperse
in due course ought to do the trick.

Franz