The keg is new, the 75/25 - Nitrogen/CO2 tank is new and just filled, all of the parts are new. The pour looks great and the head on the beer is fine. PSI is 32 and the temp is 36-38F. Everything looks good, it looks and cascades just like at a local bar, but then when you drink the beer it has a bit of a metal after taste. I hope it isnt bad gas... but if it is, is the keg destroyed by keeping it under the pressure of the gas? Also, are there different grades of gas like Food grade? Or could it be because of the new parts and they just need to be broken in? Googling for this sort of problem doesnt really come up with many results and I hope I didnt just blow a couple hundred bucks on nothing...