"FarmI" ask@itshall be given wrote in message
...
"Chookie" wrote in message "0tterbot"
wrote:

had lots of water ourselves last year too - i'm convinced though (along
with
the natural sequencers etc) that rain is different to water from a hose.

I think it's sheer quantity. 20mm falling from the sky all over my back
yard
does a lot more than 20 mm on a tiny area -- assuming I can actually get
20mm "rainfall" from my weeper hose.

The difference between rain and water from the hose is that rain has
nitrogen in it. Dunno where I first read this but I read it years ago.

i was thinking it was aeration! (or perhaps some result of aeration). but i
don't think chookie's completely wrong either - when all the area is
watered, it will stay watered longer as the water's not travelling sideways
into the dry parts, as happens when one hand-waters.

but really, all i know is that rain is 100% better than any other kind of
watering, ime.
kylie

I thought I'd better provide an authoritative cite but don't know if any
of this qualifies except for those who have fish ponds :-)) :
"Blanketweed after Rainstorms. Why should this happen?
We are certain it occurs, at least in part, because of something we have
all heard about. The key to this phenomenon is acid rain. I would suggest
that most of us have not fully appreciated the significance of acid rain
in keeping ponds. Acid rain arises from two types of acid-forming
materials. One is from sulphur dioxide that rises into the atmosphere
primarily as a byproduct of industrial processes and from the burning of
fossil fuels. From a pond keeping and algae growth perspective, these
sulphur products are not important.

The second acidforming group of gases that rise into the atmosphere are
the nitrogen oxides. These include nitric oxide (NO) and nitrogen dioxide
(NO2). When these oxides (NOx) are dissolved in rainwater high in the
atmosphere, mainly nitric acid (HNO3) is produced. This dilute acid falls
to the ground when it rains and produces nitrate in ponds.

The sudden rush into growth of blanketweed after a rainstorm is therefore
explained.

Another nitrogen compound that drops out of the sky when it rains is
ammonia. It falls to the ground and into ponds as dilute ammonium
hydroxide (NH4(OH)). It is an alkali, not an acid and the amounts are
generally less significant for pondkeepers than is the nitrate arising
from nitric acid. It is interesting to see that ammonia, one of the
products pondkeepers are removing from pondwater through their filters,
can appear in the pond water when it rains as well as from fish excrement.

The National Atmospheric Emissions Inventory
The website (www.naei.org.uk) of the National Atmospheric Emissions
Inventory (NAEI) gives a good deal of information about the amounts and
sources of various atmospheric pollutants by geographical region. Another
set of data that is available from the NAEI website is a table that shows
the annual tonnes of different pollutants emitted from various large point
sources situated within different distances from a particular postcode.
Much of the data has been produced from models used by the NAEI although
some have been provided by the owners of the plants in question.

Pondkeepers can access this tool by going to
www.naei.org.uk/mapping/mapping_2004.php and entering their postcode in
the appropriate box. We suggest that pondkeepers go into the NAEI website
and look further into the emissions that might be personally affecting
them by using their specific postcodes.

Going back to the original question of whether tapwater or rainwater
should be used for topping up ponds, the recommendation is the pondkeeper
should check particularly for nitrate (and other nasties) in both types of
water sources and, if possible, use the one with the lowest content.
Pondkeepers also have to bear in mind that levels may fluctuate so regular
checking is advisible. Better still, if pondkeepers practise water changes
to simply lower the nitrate level in the pondwater, then they need not
change large volumes of water because pond products, for example VirescoT,
are available that will take the nitrate level down to zero and hold it
there. Once nitrate is removed, blanketweed and other algae stop growing.
However, there is no substitute for keeping on top of regular pond
husbandry." http://www.practical-water-gardens.c...ateinwater.htm