Mid fermentation SG readings

[slanderkin]

I'm curious on how people take SG readings during fermentation to know when to cold crash for stopping at a specific ABV/residual sugar. Is the best way just a good ole fashioned siphon to a hydrometer and then read from there? Does putting the hydrometer bobber straight in the fermenter have merit? Also I'm curious if the bubbles produced during fermentation will impact these buoyancy readings or not.

 

[Chalkyt]

I just take a sample with a turkey baster (i.e. el-cheapo wine thief) but you have to degas the sample (quick spin in a microwave oven or just stir and let it sit until the C02 bubbles don't stick to the hydrometer). I use a "finishing" hydrometer with big graduations for this as by then the SG can be below 1.020 and the normal triple scale units can be a bit hard to read accurately.

 

[jdauria]

In regards to bubbles, yes they will throw off a gravity reading slightly. What I do is splash the sample back and forth from one glass to another 10 times or so to get the CO2 out of solution. Then I wait a few minutes for the bubbles on top in the glass to disapate and then pour the sample slowly back into the hydrometer tube and take the reading. Option 2 is just pull a miniscue sample, drop a few drops on a refractometer, take a reading and then use a refractometer online calculator, or if you use brewing software, the one that is included, to account for alcohol being present to calculate the actual gravity of the sample

 

[Climb]

A techy solution is to use one of several wireless hydrometers like Tilt, iSpindel or RAPT Pill, not that they don't have their own set of problems/challenges. I typically prefer low tech solutions, so yeah take a sample from the fermenter one way or another. I wouldn't ever put a hydrometer in a fermenter for several reasons.

 

[BongoYodeler]

Rapt Pill for me, I like the idea of not having to open the fermenter with beer in it. To answer your third question, yes bubbles/krausen can affect the Pill's reading a bit, but I'm not concerned about one individual reading. The graphical output shows where you are in the fermentation process quite accurately.

 

[bwible]

I have a Tilt and I love it. Yes, it has a couple issues like the biggest one being foam and crud get stuck to it. It measures gravity by the angle it floats at. So crud stuck to it can affect the reading by a couple points. Its not the end of the world.

It has its own software. I have mine connected by bluetooth to an old iphone that sits near the fermenter. It logs readings however you set it and sends it to the cloud. You can monitor it from anywhere. I set mine to log every 30 minutes. It monitors gravity and temp. You can see gravity and temp anytime. And it creates a nice chart. I put one at the end from the Octoberfest I just made.

The biggest drawback is they’re about $135 each. I only have one, but the software will monitor multiple. They come in “colors” so you can tell them apart. Mine is green. If I bought another one it wouldn’t matter as long as the second one is not green.

 

[JohnDBrewer]

If you want to go old school, after I pitched the yeast I pulled a sample for testing. Kept that sample in a beer bottle with foil on top next to the fermenter. When I wanted to play, I would pour the sample into the hydrometer tube and test it, then put it back in the bottle. That way I was never messing with the fermenter. Worked fine for a good approximation of what the actual fermenter was doing. If I remember right it always seemed to run a little ahead of the actual fermenter, but close enough. When it was done, just dumped out the sample.

 

[Maylar]

Just give the hydrometer a spin with your fingers to break the bubbles away before taking a reading. It'll be close enough.