"RichToyBox" wrote in message
news:lIVVb.264673$xy6.1336469@attbi_s02...
Copper will oxidize, though slowly, and the oxide will enter the water.
It
is very toxic once it reaches a certain concentration. When I started
with
aquaria about 30 years ago, the only cure for many of the parasites was to
put copper pennies in the water, and when the fish started to roll, do a
major water change. If it almost killed the fish, it probably killed the
parasites.
snip

So is it safe to assume the water 'standing' in normal household pipes is
not a problem because it is changed so often? Back to the drawing board I
guess.

BV.
www.iheartmypond.com