Testing Gravity during the fermentation

[davper]

Hi
How do I test gravity while it is in the carboy without introducing oxygen?

I have both a refractometer and a hydrometer.

 

[jrgtr42]

Carefully.
No, Honestly, there's really no reason to continually check gravity during fermentation.
Once you're getting to the end, though is when you want to check.
Basically, try to disturb the beer as little as possible. Refractometers aren't great at checking fermented beer gravity - the alcohol throws things off, but if you have your OG there are online calculators to convert.
If you want to use the hydrometer, you need a thief (sanitized of course) to get the beer out. You don't really want to start siphoning, but you can. Again be careful not to disturb the air inside any more than you have to.
Personally, I leave my beer untouched till about 2 and a half weeks after brewing. Presuming there's no activity visible (I do use buckets most of the time) I'll open it, again being careful, and I'll put my (sanitized) hydrometer right in. I'll get the reading, then seal it up leaving the hydrometer in there. 2 or 3 days later check again and presuming it reads the same, it's bottling / kegging time.

 

[Mainer]

^ +1
Get a thief. https://www.midwestsupplies.com/fermtech-wine-thief

There's no way to do it without introducing oxygen, but a thief will help you minimize the introduction.

The fewer times you do it, the better your beer will come out, so in general, you don't want to test your gravity until you start to suspect fermentation might be finished.

 

[SlitheryDee]

Yeah a wine thief works pretty well. I do think that taking gravity samples more often is taking a risk, but I guess it's also a good way to get a sense of how fast your fermentation is going as well. Just understand that you're risking infection and oxidation by doing it. Honestly I don't think oxidation is such a big deal typically, but an infection will usually cost you the whole batch. You certainly don't want that.

 

[Brewmeister10]

I agree with the above posts. No need to test your gravity until you think the fermentation is at or near the end. After CO2 bubbling has stopped, I usually wait another day or two, and then use a sanitized wine thief to check the gravity with a hygrometer. Do not empty the contents of the wine thief back into the batch, but into a glass, then look at color, check fragrance, and taste it to make sure nothing is off.

 

[raysmithtx]

I use one of these. No need to even open the fermentor. Sends the data directly to a cell phone and to a online spreadsheet.

https://tilthydrometer.com/

 

[Bean]

just get a conical, youre worry free after that