treating for ick have a few questions???

[tmkx3]

I have been treating for ick with coppersafe for 3 weeks now. My tang has a single white spot on his fin. The one he uses to swim with(Don't know the technical name for it). Is this still ick? He has been clear of all spots since the third day of treatment. I had to top my tank off with ro/water last week. Does that effect the copper levels. It seems like the test was just slightly lighter when I tested but I don't want to over medicate. Can this be something else?

 

[Fluff]

I've never used a copper med so I don't know. How long does coppersafe say to treat? If it's just one spot on the caudel fin then it could be a bacteria or fungal infection. If that is the case, with improved water conditions, it could clear up on it's own.