On Thu, 6 Jun 1996 03:39:02 -0400, Aquatic-Plants-Owner at actwin_com wrote: >If there >is Copper in the water, how could I safely remove it (ie. pretreat >the water) without leaving compounds that might also precipitate >my Fe(EDTA)? Two options: A cation exchange resin (like the "purifier" cartridges) or charcoal. Both are pretty good at ditching heavy metals. Dave Gomberg, Experimenta San Francisco CA USA gomberg at wcf_com