Seachem Cupramine is by far the safest copper medication to treat Ich and other parasites. I usually dose to level of 0.3 for 2 weeks, redosing every water change to maintain the concentration. Usually fish will b cleared of whitespot on 3rd day, but will still continue the treatment to kill off those free swimming ones. You need a reliable testkit too, I find Salifert and Seachem testkits to be the best. Though I prefer Seachem as it easier to read, but not as easily available compare to Salifert... On a side note, my skunk cleaner shrimp survived 2 bouts of 0.3 copper treatment.