I have a tetra that has ick so I got some coppersafe to treat it, but I'm not sure about the directions. It sounds like I'm supposed to just put in once and add to any water changes but it's supposed to treat the water for like a month. Does it just stay in the water that long and I don't need to add any more after the initial amount? I took out my carbon filter media as per instructions. I'm sorry if this seems like a stupid question, but I just want to make sure I'm doing it right, I don't want to lose any fish. Thanks in advance!