When I am preparing C.S., I use room temperature (about 68f) steam distilled water. I also use a precision DC generator to control applied voltage (4 -9volt batteries are also just fine). However, I have found that producing C.S. at a current controlled low voltage (24 - 28 vdc) removes almost any aftertaste (metallic or otherwise). I have a personal theory that when the voltage is increased the size of the silver particles increases; I can't prove this, it's just an idea. I think discovering the dosage for a specific ailment is purely empirical --you try a given dose and watch the effect --success also depends on the source of the disease state (type of organism), the health of the individual (immune system), and the quality of the C.S.