In article , "Weeble"
wrote:

I have a copper fire pit which has never been used and likely will never be
used for fire. I would like to turn it into a small water garden with
small waterlily and a few other plants and a small fountain. Any ideas on
the suitability of the copper for a water garden? And any ideas on plants
which woud be easy care?

Shell

A vendor at the Lavender Festival this past weekend was selling the most
artfully designed all-copper garden pools with all-copper waterfalls. Most
were shiny new copper, some were coated in verdigris, tastefully arranged
to give the impression of waves or moving water. Gorgeous, gorgeous,
gorgeous. And toxic.

A small amount of copper in an aquatic environment is probably of minimal
harmfulness -- like old pennies tossed into a pool with koi, not the best
thing to do, but not sure death either. But the entirety of the soil or
water content of a pool or marsh container being copper? Bad! Bad!

The vendor promised "no algae" but failed to mention "no fish" & "no
plants." They did however also sell waterlilies, irises, & cattails made
of brass, bronze, & copper.

The reason algae doesn't get started so easily in an all-copper pool is
because copper suppresses plant growth. It will be VERY harmful to
waterlilies. It will also kill fish, molluscs, & amphibians. Copper water
features which are for water exclusively, no flora & no fauna, will stay
clear for longer periods of time. If flora & fauna is to be incorporatged
into the pool, then copper is exactly the wrong thing.

Build up of heavy metals in water or in perepetually wet soil is extremely
slow because copper is surprisingly stable in its solid form -- build up
is faster when in contact with soil or fish poops or in circulating highly
oxygenated water. However, verdigris is very UNstable & would cause swift
toxicity, not inconceivably sufficient toxicity to harm a dog, bird, or
child that drank from such a pond (anything above 2 mg copper per liter of
water is considered safe to drink). But if such a pool were drained &
cleaned monthly, I'd wager it would be safe. I'd much rather not have a
copper fountain to begin with.

Copper pools further increase electrocution risks when pumps or lights or
filters or extension cord or anything electrical is in any way connected
to or touching the pool. You think the toaster in the glass bathtub trick
is a good way to kill someone, wait till your hand brushes against even a
dry spot along the edge of a copper pool when the pump gets a short in it.


As an aside, I don't know how deep your firepit waterlily pond would be,
but waterlilies need some pretty deep water to survive, a firepit that
deep would be rather unusual.

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
Visit the Garden of Paghat the Ratgirl: http://www.paghat.com