Taking hydrometer readings from fermenter

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jmelbye

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A common piece of advice on these forums is "use your hydrometer." So how do you guys do it? I only take a final reading when I've made up my mind it is time to bottle, and then I pour a sample out of my bottling bucket in between filling bottles. I've never had any surprises, so far so good, but I'm beginning to think this is something I should add to my practice.

I have a glass carboy and am worried about taking the airlock out and getting the beer infected. Do you drop the hydrometer in? Siphon some beer out?

Do you always take (at least) 2 readings, or if the first one is about what you are expecting do you stop there?

Cheers
 
most people use a turkey baster to pull samples.. you can get away with 2 readings. one at start and one at finish.. most mine are done at 1.010 so if i take a reading and it there i consider it done.. some people like to take two final reading a day apart to be sure its not moving. ill be the first to admit i'm a bit of a lazy brewer tho
 
I just used a sanitized turkey baster. Homebrew stores also carry wine thiefs, which are used to pull samples. Infection due to airborne spoilers are probably not a huge concern, just make sure any equipment that touches the product is properly sanitized. And it probably wouldn't hurt to work quickly.
 
I usually just use a visual inspection with hydrometer readings at the start and finish (while bottling). Typically 2 -3 weeks with an ale yeast is plenty of time to see all stages of fermentation. Little to no airlock activity and no krausen after a few weeks is a good sign that fermentation is complete (no need to take several readings unless you have an itchy hydrometer finger).
 
You'll get a feel of what goes into the fermentation process over time - but always trust your hydrometer. Measure your gravity BEFORE pitching yeast, do your temperature correction, and record it. Then your (typical gravity) beer ferment around 3 weeks (unless otherwise stated in the recipe for certain beers) and take another gravity reading. If you've hit your target, you're good. If not, try searching 'stuck beer fermentation'. You'll get a ton of discussion on the subject.
 
I have been doing similar to what dankbeer says - take a reading before transferring to the primary and pitching the yeast, and take a reading while bottling. The second reading is for my records, but it is too late if some correction needs to be made - the beer is in my bottling bucket and the priming sugar has been added.

Regarding the priming sugar (corn sugar), I've seen it quoted around 37 ppg. I buy 5oz packets and add that to a 5 gallon batch (ignoring the extra 2 cups of water the priming sugar is dissolved in). If math serves me right, that adds:
37 points / pound / gallon * (5 / 16) pounds / 5 gallons = 2.3125 points which is more than I realized.

So if my last recipe had a FG of 1.014 while I was bottling (after the addition of priming sugar), the gravity before adding the sugar would have been around 1.012.

I appreciate the replies. I don't currently have a turkey baster to pull a sample out of my carboy, but those look cheap enough. But that refractometer looks pretty slick...
 
jmelbye said:
I have been doing similar to what dankbeer says - take a reading before transferring to the primary and pitching the yeast, and take a reading while bottling
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IMO, both of these are poor times to take readings, if they are your only readings - depending on your process.

If you take your initial reading before the wort is in the primary, how are you aerating and properly mixing it for the hydrometer?

If you waiting until you are bottling to take a FG reading, what if it's not done or got stuck?

For my process, I chill the wort, pour into my primary, aerate very well, then immediately take my OG reading. I take a FG reading sometime around 3 weeks, depending on the brew - and IF it's done, I will consider bottling.

Maybe I misunderstood your post, but if not - I suggest giving it a second look.
 
Sulli said:
If your budget allows, these are the way to go.

Only takes a single drop of liquid.
Click to expand...

This is only good for SG or OG. This does not work after alcohol its present. Well it does but not without a excel calculation that is a PITA
 
NineMilBill said:
If you take your initial reading before the wort is in the primary, how are you aerating and properly mixing it for the hydrometer?
Click to expand...

I had not given the effect of aeration on the gravity reading much thought. My beer goes from my kettle into my bucket with spigot. I believe it gets a lot of air in that transfer. I slow the pour down at the end to try and leave the gunk that fell to the bottom of the kettle behind. Then I open the spigot and transfer the wort into the fermenter. I position the fermenter so that the hose coming out of the bucket is only about 3 inches into the carboy, to get some good splashing. Before it gets to heavy, I'll give it a couple shakes too.

What is the effect of aeration on the gravity? Would I tend to get higher gravity readings if I took my sample from the carboy?

NineMilBill said:
If you waiting until you are bottling to take a FG reading, what if it's not done or got stuck?
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I agree, and that's why I'm asking how you guys typically take your readings. I have not had any stuck fermentations yet. I'm limited in space and supplies (1br city apartment brewing) so I'm pretty much confined to ales around 1.04-1.06 starting gravity. Typically my beers are in the 1.045 - 1.055 range.

I've not made a practice of taking readings from the primary because I don't have a good way to get a sample out. A turkey baster seems easy enough, provided it reaches far enough. Even though you need a larger sample, I think I like that more than the refractometer because in addition to being cheap, it allows me to taste and smell the beer.
 
I have found different yeasts will behave so differently and different brews (OG mash temp) can make the same yeast behave differently, that I take a couple of readings though out the process, I find this a great way to sample to favors and see how the beer is developing. I use a turkey baster, I keep a bucket of starsan in my brew room so I can leave the baster soak for a good period before use. Same to a glass container and you can check clarity taste smell etc. While I'm sampling I put the bung and airlock in the star san (rinse if it first if it has krausen on it) the brew gets covered with santized foil while I have the air lock off removed only for the time the baster is in the carboy.

This process I use to minimize exposure, I'm not concerned with microbes effecting my beer with this process, I have been doing it for years with no problems. You have to look at the way nasties get into your beer, they get in their through air currents bring them in or by hitching a ride on equipment by minimizing open time and using completely sanitized equipment the bugs don't have a chance. Also fermented beer does not support many organisms as the acidity is too high only a few nasties will live in there, so just don't leave the door open too long and they won't cause you a problem.


Clem
 
Well maybe I'm not thinking about this correctly, but aeration, it seems to me, only distorts your gravity reading? I could make two identical worts, with the same sugar, protein, etc. content. The only difference is one has twice as much air in it.

If you allow me to say it is given that they both fully ferment (I know you might say the second is more healthy and might ferment further, but let's say that was controlled), then they would end at around the same final gravity. Would it be correct for me to say that one has a higher ABV because the original reading had more or less air in it?

Now if it is just convention, or the ABV, ABW calculations are "calibrated" for aeration, I can understand that.
 
When I asked how you are aerating your worting - it went hand-in-hand with the second part of the sentence - mixing the wort. You want to mix it well (shaking the crap outta the primary, aeration stone, whatever) to ensure you have an even distribution of sugars throughout the entire primary, so that your sample for your hydrometer is accurate in respect to the batch as a whole.

The greater the aeration, the healthier the ferment, the easier it is for the yeast to do their job. Will this equate to a higher ABV? Possibly, but minimally if at all. In a low gravity wort, a healthy, qualiity yeast should have no problem eating all the sugar in the primary. The difference will come in the health and quality of the ferment. You are shooting for a fast and violent ferment (read: healthy) - and increasing the oxygen in the wort is increasing food for the yeast.
 
chezzesteak said:
This is only good for SG or OG. This does not work after alcohol its present. Well it does but not without a excel calculation that is a PITA
Click to expand...

I use this calculator to adjust the brix reading when alcohol is present.

Makes life real easy, and I'm not dumping half a beer down the drain every time I need to take a gravity reading.
 
NineMilBill said:
When I asked how you are aerating your worting - it went hand-in-hand with the second part of the sentence - mixing the wort. You want to mix it well (shaking the crap outta the primary, aeration stone, whatever) to ensure you have an even distribution of sugars throughout the entire primary, so that your sample for your hydrometer is accurate in respect to the batch as a whole.

The greater the aeration, the healthier the ferment, the easier it is for the yeast to do their job. Will this equate to a higher ABV? Possibly, but minimally if at all. In a low gravity wort, a healthy, qualiity yeast should have no problem eating all the sugar in the primary. The difference will come in the health and quality of the ferment. You are shooting for a fast and violent ferment (read: healthy) - and increasing the oxygen in the wort is increasing food for the yeast.
Click to expand...

Is this something you actually have observed, or just a precaution? I wouldn't think that the relatively small amount of time it takes to cool the wort after a boil (which mixes the solution quite well) would lead to any sort of significant difference in sugar concentration at the bottom of the kettle (versus the top).
 
bolshoifish said:
Is this something you actually have observed, or just a precaution? I wouldn't think that the relatively small amount of time it takes to cool the wort after a boil (which mixes the solution quite well) would lead to any sort of significant difference in sugar concentration at the bottom of the kettle (versus the top).
Click to expand...

This is something I observed countless time in my first couple of brews, but luckily I did not worry about it because of the ridiculous amount of hours I spent on HBT reading (much to SWMBO's demise...)

Not only this, but Revvy - a beginner's best resource on this entire site - has written a blog about the issue of sugar distribution throughout a primary fermentation because the question is so frequent.

If you have not read it before, do so, and educate yourself.
 
NineMilBill said:
This is something I observed countless time in my first couple of brews, but luckily I did not worry about it because of the ridiculous amount of hours I spent on HBT reading (much to SWMBO's demise...)

Not only this, but Revvy - a beginner's best resource on this entire site - has written a blog about the issue of sugar distribution throughout a primary fermentation because the question is so frequent.

If you have not read it before, do so, and educate yourself.
Click to expand...

If you pour a bunch of water in (or dump a bunch of sugar in) after the boil, then of course it will lead to unequal distribution. I don't think I'm alone in interpreting your above statements as applying to all cases.

To be clear, there shouldn't be any significant difference in gravity readings between a reading in the kettle and a reading post aeration if you are not doing post-boil water addition.
 
bolshoifish said:
To be clear, there shouldn't be any significant difference in gravity readings between a reading in the kettle and a reading post aeration if you are not doing post-boil water addition.
Click to expand...

It's my personal practice to apply these concepts as a precaution to get the most accurate reading. If you dump your cooled wort into your primary and immediately reach for your turkey baster/wine thief - sure - the sugar probably has a good mix. But this is probably dependent on your process. I use a large funnel to pour my wort into my carboys. It has a detachable mesh screen that filters some gunk out (hops, cold break, boil-additions, etc.). This filter will convienently clog up once I've added in about 4.5 of my 5 gallons to the primary. This means the pouring process is halted for a little bit while I take extra time to unclog the filter. Is the amount of sugar falling out in this amount of time a lot? Probably not. But I only have a one way of measuring that sugar mixture - and that's my hydrometer. By ensuring I aerate/mix my wort after it all has been added, I get all of my batches on the same 'level' and do not have to wonder if sugar distribution will play a factor in my numbers and record keeping.
 
NineMilBill said:
It's my personal practice to apply these concepts as a precaution to get the most accurate reading. If you dump your cooled wort into your primary and immediately reach for your turkey baster/wine thief - sure - the sugar probably has a good mix. But this is probably dependent on your process. I use a large funnel to pour my wort into my carboys. It has a detachable mesh screen that filters some gunk out (hops, cold break, boil-additions, etc.). This filter will convienently clog up once I've added in about 4.5 of my 5 gallons to the primary. This means the pouring process is halted for a little bit while I take extra time to unclog the filter. Is the amount of sugar falling out in this amount of time a lot? Probably not. But I only have a one way of measuring that sugar mixture - and that's my hydrometer. By ensuring I aerate/mix my wort after it all has been added, I get all of my batches on the same 'level' and do not have to wonder if sugar distribution will play a factor in my numbers and record keeping.
Click to expand...


Not to be pedantic, your process is what works for you and I'm not trying to change that, but the fact that we are way under the supersaturation point of sugar and water and diffusion ensure that you never have to worry about the sugar content being lower. Sugars simply don't "fall out" (as you say above) of a solution at the sugar levels we are dealing with. Once mixed, without addition of other outside variables (like more sugar, or more water), the solution remains homogeneous.. over any length of time.
 
bolshoifish said:
Not to be pedantic, your process is what works for you and I'm not trying to change that, but the fact that we are way under the supersaturation point of sugar and water and diffusion ensure that you never have to worry about the sugar content being lower. Sugars simply don't "fall out" (as you say above) of a solution at the sugar levels we are dealing with. Once mixed, without addition of other outside variables (like more sugar, or more water), the solution remains homogeneous.. over any length of time.
Click to expand...

Assuming that's true (I'm NOT a science guy by any means) - that's news to me. I've come to my method of brewing based upon countless research on HBT. I'll put your post in my back pocket and consider it "another tool in the tool-belt" until someone proves otherwise.

Appreciate it, bolshoifish. :mug:
 
Did anyone say use a "wine thief" to get that sample for the hydrometer. And you get a little sip to see how its going.
 
mikescooling said:
Did anyone say use a "wine thief" to get that sample for the hydrometer. And you get a little sip to see how its going.
Click to expand...

I just got one. I assume you don't want to press it on the bottom and suck up sediment. Do you press it against the side wall?
 
Tried out my turkey baster today. It doesn't hold the liquid very well - it drips while I try to get the sample out. I can't imagine a couple drops will have much impact in terms of oxidization, but I sure wish that didn't happen. The baster also only made it into my beer by maybe 1/2 inch at the most (5 gallon recipe in 6.5 gallon carboy). Oh well. On the plus side, my gravity is looking right on target.
 
Wanted to put my two cents in. I think hydrometer readings are useful in the pre-fermenation at sparge, pre-boil, and right before pitching yeast. All these times will help you refine your process. During fermentation, I leave it alone. When I think fermentation has slowed to close to terminal, I'll check gravity. I think understanding all the visual signs, which do point to what is going on at the bio-molecular level are important-- krausen, release of CO2, yeast falling clear, etc. You can start to understand how particular yeasts behave by keeping an eye on things. That's a nice advantage of a carboy.

I keep my process for gathering samples post-fermentation very clean: have sanitizing solution available. Don't let stoppers, your hands, air locks, or anything else come in contact with the mouth of the fermenter without being sanitized. My system is a lot more pirimitive, though, than even using a thief or turkey baster. I just carefully pore a 1/2 cup off into a pyrex container, pour that into my hydrometer flask, and then drink some! I don't think the small amount of oxygen in splashing is a concern. I have a feeling (not necessarily justified by science) that the CO2 that is still being produced will carry away oxygen before it can effect the nearly fermented beer. That's my two cents!
 
jkendrick said:
I just got one. I assume you don't want to press it on the bottom and suck up sediment. Do you press it against the side wall?
Click to expand...

No, you just shake it up and down, touching nothing. The beer/wine just climbs it's way up the inside. I don't know how it works, but it works.
 

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