"Two and a Half" wrote in message
...
Most base element metals such as Aluminium and copper in water are totally
inert and they have no effect on any aquatic life in your pond. Unless
stainless steel is of a really high quality it will eventually rust,
resulting in iron oxide being leaked into your pond. This wont do your
fish
much good as it can starve your pond of oxygen if large quantities are
present.

Also remember firstly fish are able to determine movement by reflection of
light on the pond surface and secondly they only have about a three minute
memory span. A heron will remain perfectly still for ages and will only
wait
for the fish to re-emerge from their hiding place before catching his next
meal. I would surmise that unless the crate is at least 60cm below the
surface of the pond the heron will probably use it to perch on and gain
his
next meal.

Craig

Don't know were you get this 3 minute memory span from, but I can assure you
it is a fallacy.

Bryan