Hydrometer - I think I get it... but why?

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nickhead

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Hey guys,

I think I understand the concept of the hydrometer / gravity readings (to gauge alcohol content).

What I don't understand is...

I take a reading before I pitch the yeast. I take a reading a couple times maybe during the fermentation process... but why? If I find that the gravity readings are undesirable or off or whatever, what do I do to address the issue? Or - do we use a hydrometer JUST to know what the alcohol content is or is there more to it? Perhaps if the gravity shows a lower alcohol content than desired I'd use more sugar during the bottling process (maybe)?

It seems that regardless of the readings, my beer is going to turn out the same whether I check the gravity or not. Is that incorrect?

I kind of get it - but kind of don't.

Thanks,
Nick

ps. I haven't checked the gravity of my first brew. It's been 4 days - should I check it now?
 

Mutilated1

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Well not only can you sort of check the alcohol content, the hydormeter will tell you when the beer is finished and when you need to wait a day or two more.
 

Orfy

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It is to back up what you know/feel/guess
The less you know/feel/guess the more you need the reading.

It's like secondary, if you don't have the experience to decide for your self then got for it.

You'll find most of the time if the hydro reading is not desirable then either you've not given it enough time or the condition/actions are not adequate and need intervention.



It doesn't actually check alcohol. It checks the reduction in gravity which is an indication of the production of alcohol.
 

Laurel

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A good reading for a reading after fermentation is to be sure that fermentation is complete. If it's not (your gravity is higher than expected), then you know not to put it in bottles and deal with the resulting bottle bombs. Then you can troubleshoot a stuck fermentation and try to address the issue.

Some people swear by hydrometers, and it's important to know how to use one and use it for a while. Some people are lazy and have been brewing long enough to feel safe determining whether the beer's done without a hydro.
 

ohiobrewtus

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As a general rule I take a reading when it goes into primary then again when it goes to keg/bottles. If it's the first time that I've brewed a particular style I may also take a reading when I rack it to secondary to ensure that I'm within the FG range for the style.

I've never seen the sense in taking multiple readings from primary, but to each their own. You could wait and take a reading before you rack to secondary and if your SG is high then you could always pitch onto a neutral cake or re-pitch to see if you can get it down.

Normally I give everything 10-14 days in primary and it works out well for me.
 

Rezilynt

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I think I take a reading a couple times maybe during the fermentation process... but why? If I find that the gravity readings are undesirable or off or whatever, what do I do to address the issue? Or - do we use a hydrometer JUST to know what the alcohol content is or is there more to it?

It seems that regardless of the readings, my beer is going to turn out the same whether I check the gravity or not. Is that incorrect?

ps. I haven't checked the gravity of my first brew. It's been 4 days - should I check it now?
Let me try and helpexplain and others will also put in their two cents:
The reason for the readings during fermentation is to see if the fermentation is complete. You really don't want to take readings every day or every other day - just when you think it is done. This can be a set number of days (7) or more. The more you brew, the better you'll be able to guestimate this. (It's kind of like cooking a steak on the grill - the more you stick it with a thermometer to get a temperature reading, the worse the steak taste. You get to a point where you are pretty sure it's done and then take the reading).

Back to beer - When you believe the fermentation to be finished, take a reading once a day for 3 days. If the reading is the same on all 3 days, you can bet the fermentation is finished.

I would wait a few more days to start checking your final gravity.

I have got to start typing faster - 4 posts while typing this one.
 

carnevoodoo

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Just as a note that I don't think I've seen the others make, do NOT add more sugar than indicated when bottling. Your bottles will become weapons very quickly.
 

BierMuncher

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A hydrometer is like your beer compass.

OG - Where are you starting?
Mid Readings - Are you on course?
FG - Where did you end up?

The mid-readings may be a luxury, but certainly the OG and FG are important to help you adjust your system/processes, improve efficiency and zero in on your attenuation targets.

If I didn't have a hydrometer to tell me my beer attenuated too low, I wouldn't have drawn the correlation between longer rest times during my mash, and dryer tasting beers.

IF you don't know your efficiency on the last batch (which requires an OG reading), you can't very well put together your recipe for your next batch. Shot-in-the-dark brewing may be fine if you want to brew something that "tastes like beer", but honing in an exact clone or replicating that magical batch you came up with two months ago will be near impossible without a "road map".
 

Laurel

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I wish there was a beer GPS. Then we wouldn't have to take readings and a nice Australian woman's voice would tell us when we've arrived.
 

david_42

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I wouldn't bother taking a reading until you hit 7 days AND the airlock has stopped bubbling.

Sometimes, I just leave the first sample on the counter with the hydrometer in it. That gives you a continuous reading without taking more samples. When the reading has stopped changing, I'll check the fermenter.
 

DuffmanAK

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I'm of the opinion that you want to open that fermentor as little as possible. So if I'm keeping it in primary for 4 weeks, the last 3 days of that 4th week I take hydrometer readings. Other than that, I just leave it in the closet and not touch it :)
 

BrosBrew

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I wish there was an internal and digital hydrometer. You waste a 1/3 of a beer every time you take a hydro reading so if you take 4-5 hydo readings, that's... well... you do the math.
 

carnevoodoo

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I wish there was an internal and digital hydrometer. You waste a 1/3 of a beer every time you take a hydro reading so if you take 4-5 hydo readings, that's... well... you do the math.
I only ever take two. I know when my beer is done at this point, so I use my second check just to record my gravity so I can take notes. But I wouldn't think I'd do more than 3 otherwise.

Some people do use refractometers too, but I'm thinking I will avoid that just because it seems like the calculation is tricky and not always accurate.
 

HBHoss

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For me taking a hydro reading is a chance to taste my beer. I figure if it tastes good when it's flat and warm, then it should taste great when it's carbo'ed and cool. :D
 
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nickhead

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Interesting. Thanks guys. I applied this to my most recent batch.
 

Grinder12000

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Well - here is the thing (for argument sake)

IF you are goign by a recipe or kit - then the OG is a known correct? at least very very close.

Then of you leave the wort in the carboy for 3 weeks you are pretty sure it is done fermenting . . .correct? How often does fermentation last more then 3 weeks ???

So if a person is "lazy", is workign on a known recipe of kit. I don't see why a hydrometer reading is needed.

PLUS - I can not take an OG anyway. I dilute my partial boil with 34 degree water and get layers. Unless someone knows how I can mix a 6g carboy - certainly can not put it over my head and shake it!
 

Yooper

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Well - here is the thing (for argument sake)

IF you are goign by a recipe or kit - then the OG is a known correct? at least very very close.

Then of you leave the wort in the carboy for 3 weeks you are pretty sure it is done fermenting . . .correct? How often does fermentation last more then 3 weeks ???

So if a person is "lazy", is workign on a known recipe of kit. I don't see why a hydrometer reading is needed.

PLUS - I can not take an OG anyway. I dilute my partial boil with 34 degree water and get layers. Unless someone knows how I can mix a 6g carboy - certainly can not put it over my head and shake it!
You're right- you probably don't need a hydrometer reading. Unless.........fermentation didn't completely finish and the beer is "stuck" at, say, 1.025 and has been for three weeks. You can't tell from looking at it. You prime it and bottle it, thinking it's done because it's been in the fermenter three weeks. Priming and racking rouses the yeast and the bottles turn into grenades and blow up. I bet someone would say, "Boy, maybe I should have used a hydrometer to ensure fermentation was finished.".
 

CBBaron

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So if a person is "lazy", is workign on a known recipe of kit. I don't see why a hydrometer reading is needed.

PLUS - I can not take an OG anyway. I dilute my partial boil with 34 degree water and get layers. Unless someone knows how I can mix a 6g carboy - certainly can not put it over my head and shake it!
To mix you beer, and aerate in the carboy, try this:
Wine Degasser/stirrer

It works great for my meads where I have to mix a gallon of honey with 4 gal of water at room temp. I don't want to contemplate have to do that by hand even in a bucket.

I have not had a problem with stuck fermentations and they shouldn't be a problem with normal strength beers that use good yeast with proper aeration. So a hydrometer is not "really" needed. However it is always good to know what your beer finished at and if AG what your beer started at. These numbers let you know attenuation rates and efficiency and ABV. ABV is just a nice to know number but attenuation and efficiency can be used to tweak the beers for better results.

I usually take an OG measurement and a FG measurement 3+ weeks later at bottling. Right now I am happy with my efficiency (80%) but my attenuation has been low even when going for drier beers. I think the 64F temps in my basement may be partially to blame but I am also considering extending the mash time.

Craig
 

Laurel

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I just put a doubled up, sanitized piece of saran wrap over the top and hold it in place with my hand, then put the carboy on a towel on the kitchen floor, the kneel down and shake the bejesus out of it with 1 edge of it on the ground. Works like a champ!
 

TheFlatline

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To mix you beer, and aerate in the carboy, try this:
Wine Degasser/stirrer

It works great for my meads where I have to mix a gallon of honey with 4 gal of water at room temp. I don't want to contemplate have to do that by hand even in a bucket.
That thing is freaking hardcore. If you use carboys or better bottles, just fire that sucker up, and let 'er rip! If you're using a bucket, caution is needed, as you can easily slosh most of your wort out of the bucket.

They say to not "pump" the mixer, but I imagine that's because they don't want you to oxygenate your wine.
 

TheFlatline

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I wouldn't bother taking a reading until you hit 7 days AND the airlock has stopped bubbling.

Sometimes, I just leave the first sample on the counter with the hydrometer in it. That gives you a continuous reading without taking more samples. When the reading has stopped changing, I'll check the fermenter.
The airlock is okay only if you are keeping your temperature fairly consistent. If the beer warms up, or cools down, the outgas will be different. If I waited for the hefe to stop bubbling, I probably would have waited for a month.

The hydrometer said it was done though, which is fine for me.
 

Grinder12000

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Originally Posted by CBBaron View Post
To mix you beer, and aerate in the carboy, try this:
Wine Degasser/stirrer

It works great for my meads where I have to mix a gallon of honey with 4 gal of water at room temp. I don't want to contemplate have to do that by hand even in a bucket.
AWESOME - that is exactly what I was looking for but did not know existed.

Thanks
 
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