If carbon removes heavy metals, then would it remove some of the trace
elements that we add to the tanks?

It could, and that's what people worry about. That's why many people remove
the carbon from their filters. (If you have something like a Whisper, where
the carbon's built into the pad, there's alternative media sold for it, that's
carbonless.)

Practically speaking, though, I suspect you have to have a lot of carbon, and
you have to change it every few days, before it absorbs so much it makes a
difference.



Leigh

http://www.fortunecity.com/lavender/halloween/881/