I'm
just wondering why you shouldn't use copper base med in a planted tank ??
Copper is poisonous to plants. At least, more so than malachite green and
formalin. It won't cause immediate problems, but you may notice damage to the
plants a few weeks later.
Also, many planted tank keepers have snails and shrimp in their tanks. As you
noticed, copper is very toxic to invertebrates.
Leigh
http://www.fortunecity.com/lavender/halloween/881/