I just started cupramine yesterday and the instructions are to put two drops per gallon and wait 48 hours and add an additional two drops per gallon and then monitor the copper level. The concentration should be .5 mg/l after second dose. From what I've read in does not become lethal until .8 mg/l of copper. Also someone stated that when you do a water change you should add the cupramine to the fresh saltwater before you add to tank as apposed to adding fresh saltwater and then adjusting for copper level.