I have an angel fish in a QT. Im adding "odin ex" to the QT to treat ick. (Guy who works at the Chicago Shedd Aquarium said it was good stuff, so I took his word for it) Anyway, It needs to be in there for about 10 more days. He said not to do water changes while the fish are in a QT. I just checked my NO3 levels, in the QT, and they are high. Should I do a water change? Wont this defeat the purpose of medicating it? Acoording to Red Sea test my NO3 level is at 20 on the low range side.