Kevin Conlin says.....and >George Booth added: > >> A long time ago, we used a UV sterilizer (thanks to the well meaning >> but money hungry fish store) and determined that is was removing, or >> making unavailable, the iron in the water. Turn it off. I think George has answered your question with regard to the lack of measurable iron in the water. FeEDTA and FeDTPA are very soluble in water and are not precipitates. --