After treating tank for ich how do I prep tank to put amphibian back in?

My tank started showing signs of ich spots on three fish. I removed the carbon from the filter and temporarily moved my newt into another tank so that I could treat the tank with ich medication. The ich appears to have been eradicated. So now, do I need to do a 100% water change? Or just 50% and let the carbon take care of the rest and let it run through for a day before I put the newt back in?