checking fg

I've heard I am supposed to check the gravity a few times from the secondary to make sure that the fermentation is finished before bottling. Isn't there some risk of oxidation here if I unplug the carboy and lose all the co2? At that point in the fermentation I wouldn't think that the yeast could replace it very easily.

Co2 is heavier than air so you will not lose any. Don't worry and check your gravity

There's very little risk of oxydation as you have residual yeasts in the beer which are still fermenting on a very slow level, even after the krausen has fallen. As long as you're not breaking the surface tension of the water (which holds O2 in place below the surface) then you should be fine. Moreso if you're using a keeser or other fermentation chamber, which is likely flooded with CO2 gas from the fermentation process.

It's only when you stir up the beer (rapidly breaking the surface tension) that oxydation can become an issue. This is why it's a bad idea to stir up the beer prior to bottling/kegging, as you might introduce more O2 than the yeasts can consume in residual fermentation. The yeasts can consume a small amount of oxygen if there's more sugar to consume (ex: stuck fermentation or when priming in a bottle/keg)

The above advice is solid.

That being said, you shouldn't be fermenting any longer in the secondary; leave the beer in primary, on the yeast cake, until you reach a stable final gravity. You shouldn't need to check gravity in your secondary - secondary (aka brite tank) is used for clarifying, conditioning, and aging the beer.

I personally wouldn't think of taking a gravity reading until the beer has been in primary for at least two (if not three) weeks. You won't really risk oxidation, but you do risk contamination. Also, you are wasting precious beer with lots of samples.

homebrewdad said:

you are wasting precious beer with lots of samples.

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This is the part that breaks my heart