I made a batch of Hefeweizen about 4 hours ago and have yet to see any evidence of fermentation. The recipe said that fermentation would be vigorous and would require a blowoff tube so I figured I should be seeing some action by now? A couple things to factor in that may have an affect are that I made a yeast starter in the carboy that I am using for fermentation so I poured the worst onto it before aerating it/adding cool water. Also I have accidently knocked over the glass that the blowoff tube is in several times allowing oxygen to get in. Lastly I did not thin to mark my carboy before adding the wort and so I had to estimate based off of research online how high 5 gallons should be. Could any of these things be causing a problem or do I just need to be more patient? I've also noticed that it looks fairly dark for a hefeweizen, an opaque brown almost like a gallon of arizona tea.