HELP! how to properly take a hydromoter reading

So I am a bit confused on this, I am told not to introduce air to the wort while in the secondary ferm stage. My wort has slowed to a small bubble (airlock activity) about every 2 minutes. If I take a sample with a sanitised turkey baster wont this introduce air(by removing the cap) to the beer and possibly spoil it. I then put the sample back in cap it and hope theres enough fermentation (co2) escaping to push the oxygen back out!

how much co2 air lock activity do i need to remove the oxygen? I have a 5 gallon glass carboy and theres about 8 cubic inches of empty space.

I am then told to wait 2 more days to make sure theres no change in the gravity! what do you guys do?

Gravity readings so far are 1.036, 1.038 1.010 in that order!

Don't put the sample back in. Drink it down/ take it as a taste test.

If you are still getting bubbles it doesn't mean that you are still fermenting OR that you are done. The bubbles may just be from temp change etc.

Take your sample and reseal so little to no air gets in and then take your reading.

If I'm not tracking fermentation I usually take my 1st reading after 2 weeks, then measure it again after 2 days and keg if it is the same. I am not concerned about introducing oxygen, but I carefully take sample trying not to disturb it.

Opening the airlock will not introduce much oxygen. Just avoid doing much splashing when taking the sample. (And as was mentioned, don't put it back. Drink it so you get an idea of what is going on. Better than the higher risk of infection from reintroducing the sample to your whole batch.)

Your gravity got slightly higher from your first reading to your second - I'm not sure, but that may be a temperature effect and not a true reading. If your second and third readings are correct, it is likely finished. With some experience, you can make a judgement call, but in your case I think the best bet is to take a final measurement and make sure you are still at 1.010. If so, bottle it.

So I took my first reading from the secondary. It was higher mabey due to temp, Anyway it was at 1.012 or 1.013 it was too close to tell exactly, but for whatever reason it went up from the 1.010 it was at before transfering to secondary.

As you all stated to not put back in as it is possible that a reintroduction of infection to the beer is possible, So I didn't.

There hasnt been any activity in the airlock for about 3 days, This beer has been fermenting for about 2 weeks. If the reading is the same or lower tomarrow Is it okay to bottle. I'd like to finish this one up so I can start my next batch.

Most hydrometers are calibrated to 60F. If your hydrometer is calibrated to this temperature, make sure you are at or very close to this temperature when taking a reading. Also, you should de-gas your sample. Bubbles around your hydrometer can give a false reading. I typically leave my sample out for 20 minutes and shake it every now and then to make sure any residual CO2 is out of solution. I then cool my sample to 60F and take a reading.

UTPhish said:

Most hydrometers are calibrated to 60F. If your hydrometer is calibrated to this temperature, make sure you are at or very close to this temperature when taking a reading. Also, you should de-gas your sample. Bubbles around your hydrometer can give a false reading. I typically leave my sample out for 20 minutes and shake it every now and then to make sure any residual CO2 is out of solution. I then cool my sample to 60F and take a reading.

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Great thread - I was going to make a similar one. I like this response the best - in theory - as my hydrometers is cailbrated to 60F.

Although, is there some sort of calculation you can do to compensate for different sample temperatures? For example, if your sample is 65F, how would you adjust the reading? I'm assuming a calculator of some sort?

Also take a look at the paper that came with your hydrometer. Mine mentions the correction factor (0.001 for 5 deg and 0.002 for 8 deg - something like that, anyway).

I go 2 weeks then take a reading daily. As soon as I get the same reading 3 days in a row it's off to keg/bottle.

I don't worry about O2 contamination. The CO2 layer on the beer should act as a oxygen barrier.

I don't pay attention to the airlock activity. It's an airlock, not a fermentation meter.

I taste all my samples and never reintroduce them to the batch.