Hey all...new to the board. I have brew a few batches of extract ale and decided to try an extract lager. I purchased a chest freezer and temp. controller..both work fine. I don't know if it is because of the confined space or the WLP 830 German yeast but the airlock is giving off a sour odor. Is this normal? Maybe I just never noticed since I fermented my ales in a spare bathroom. I used a stepped up starter and have the temp at 54* F . Thanks for any help.