If I use a glass carboy for primary fermentation, how do I take periodic gravity readings without introducing oxygen to wort? My apologies for the home-brewing 101 questions but I really make sure I have as much info as possible before I start my first brew!
You just need something to get in there and grab a sample. Just do it relatively quickly and sanitize everything that touches the beer before using it.
You can go with some kind of thief like this: 3 Piece Thief - plastic
Or do what I do and use a sanitized turkey baster. The turkey baster works fine if you’re doing five gallon batches in a six gallon carboy. If your volume is lower you might not be able to reach with the baster.
What about the thought of using a satellite fermenter? (ie: using a spare sanatized beer bottle. take a sample afer you pitch/mix your yeast.) Then you can take samples at your leisure. And not worry about anything getting into that liquid gold.
In order for your satellite readings to be meaningful, its fermentation must proceed identically to the main fermentation. The differences in volume, pitch rate, etc. are going to make that pretty tricky to obtain.
I use a wine thief I purchased at my LHBS for about $10. Work very well, just sanitize first and don’t leave the fermenter open for very long.
And Dozer: Does the satellite fermenter ferment the same as the larger fermenter? Does the different weights/volumes affect the wort differently? Will one ferment faster than the other?
I also use a wine theif and have had no problems. As was stated above if you are quick there is not much danger of infection. and as long as you are gentle you will not disturb the CO2 blanket so no worries about O2
Haven’t tried the satalite trick. I saw it on a You Tube video and thought it might work. Lol, guess not. On my bucket lid of my primary i have cut a larger hole and used a bigger stopper with an air lock. Still ferments just fine. When i need to take a sample i remove the stopper, grab a sanatized thief and get my sample. Lid never comes off the bucket.
You’re going to be able to take your sample relatively quickly, especially if you use a wine thief as others have mentioned. The chances of oxygenating your brew in that time are slim to none. I wouldn’t fret. I frequently will take 3 readings 3 days apart and have never had problems. Skip the satellite batch: not worth the time as it’s not going to be a 100% representation of what’s going on in your carboy. Happy brewing!