I did some internet research about activated carbon a few months ago, and as I recall, it is most effective for "big" molecules, like organic ones, and not effective at all for small molecules, like all inorganic ones. Perhaps it removes some of the chelator in trace mixes, but I doubt it. And, I can't see any way it releases phosphate at any time - where is the phosphate coming from? It seems pretty well established that it removes medicines (all organic compounds), and tannins causing yellowed water (also organic). I think I still have several bags of it in my aquarium junk box from various filters I bought over the last 5 years, so I don't think I have ever used it, at least not in this century.