In article ,
"david" writes:
| Try a stiff broom, some sharp sand, some water and possibly a squirt
| of washing up liquid. It works a dream and isn't horrible to use.
| Why does everyone think in terms of toxic chemicals?
|
| Well in defence.....
| The sand and stiff broom may well SHIFT the algae, but it wont Kill it, so
| you will have the problem back again quite quickly,
| Formaldehyde will kill the algae and spores.

As they are ubiquitous in dust, that is only a temporary gain.
I should be surprised if it reduced the frequency of attention
needed by a large factor.

| Alternatively you could tarmac over the top......

Once the toxins have leached from the surface, algae will grow
quite well on that - and most domestic tarmac will break up if
you scrub it hard.


Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QH, England.
Email:
Tel.: +44 1223 334761 Fax: +44 1223 334679