google search indicates there is dosage info on the product. But it doesn't say what it is.
Do this: assuming you have the dosage info. Draw a 'fill line' on the glass representing the water line of the qt before dosing. The water must NEVER be above or below that line: somebody must attend to topping it off with fresh water about 4x daily, and try not to let evaporation screw it up. If the dosage wobbles due to evap or inaccurate topoff, it can kill your fish or help the ich survive. If you had an ATO (autotopoff) to devote to this tank you would be well off. Maintain that fill line rigidly and do not use a black or carbon filter on your tank: pure white only, no carbon fill: hospital cotton or pillow stuffing can work for it if you can't get a no-carbon filter. You do not re-dose: copper does not evaporate. The concentration will remain the same if that fill line is observed religiously for the treatment duration. When treatment is done, use carbon and a water change to remove the copper. And continue to observe the fish for a few weeks.