Originally Posted by RedCabbage
So "aerating" and "degassing" are the same process?
No. Aerating is the mixing in of air. Degassing is the process of getting dissolved CO2 out of solution so the mead won't be fizzy. However when you stir, swirl or shake, to aerate, some degassing will occur, and it can be be vigorous enough to cause the MEAs.
Nevertheless, degassing is mostly about getting rid of the dissolved CO2 after fermentation is finished. At that point, you don't want to mix air in, so you may use a different approach that minimizes air exposure. In my case, I will usually swirl the mead while keeping it under airlock, and letting it sit at room temp for some weeks. Like a bottle of soda pop that you leave open on the counter, it doesn't take all that long for it to become flat. Now other folks may use different ways of doing it including, using a vacuum pump, or a degassing whip attached to a drill. I don't like the drill approach because that entails opening the mead and allowing air to mixed in while you are stirring to release the CO2 (effectively the same thing you do with aeration), but many folks do this without problems.
There are some who encourage vigorous degassing during fermentation with the thought that CO2 is toxic to yeast, and degassing allows the fermentation to proceed more rapidly. Since the CO2 is only at one atmosphere of pressure, and you have to get above 7 atmosphere of pressure to significantly impede the yeast, I don't think this is true and I would ask anyone that has any data demonstrating active degassing having a beneficial effect on fermentation to please share it with us.
There is data that swirling the yeast to keep them up in suspension, or having particulate matter that functions in the same way will both allow fermentations to finish a little faster. I typically keep the fermentation under airlock and swirl it a couple of time each day to keep the yeast stirred up. That produces some degassing, which is okay. Truthfully, I haven't seen that swirling makes much difference as the fermentations generally finish about as quick either way.
So I generally don't spend time worrying about degassing. It will happen as my meads sit at room temp for a spell and get racked a couple of times. After that, they are nice and still with minimal effort. However, if you want to get something clear and bottled faster, active degassing after fermentation will speed you along, especially if you are keeping them in a cool storage area.