so right now im' fermenting a northern brewer american amber ale kit, for the first two weeks it retained a nice amber color, not 4 days into week three the color has turned into a very dark almost black shade. slightly worried that this means an infected/bad batch. this is only my second beer so i'm pretty well confused as to what's going on here, any ideas about what is up will be greatly appricated. i took one gravity sample after one week where i also switched from a blowoff tube to a bubbler type airlock. HELP!!!!