Measuring S.G. while avoiding solids

[southsidebrewer]

I'm fermenting a Centennial IPA in a 6.5 gallon bucket (no spigot) and yesterday was my 7-day mark. When I removed the lid, there was a 1.5 inch layer of "foam" (not sure of the term...but I'm sure there is one) on top of the beer which I had to navigate my way through to remove a sample. I used an auto-siphon to remove my specific gravity sample, but no matter how careful I was, I still managed to remove some trub (or "solid" material) along with the beer.

Couple questions...

1) What are my alternatives to using the auto-siphon to remove the sample?
2) How concerned should I be with the solid trub material affecting my S.G. reading?

I'm fairly sure (if I recall freshman chemistry) the additional solids will positively bias my density reading...if so, how do I get around that?

My S.G. reading at seven days was 1.025(6) and my target F.G. is 1.012(4). O.G. was around 1.07.

Thanks!

southsidebrewer

 

[Professor Frink]

1) You can pick up a wine thief to take hydrometer readings (or use 50 ml pipettes from lab like I do ), it'll make things much easier.

2) I wouldn't worry too much about the trub, the hydrometer really is only affected by dissolved sugars. You can put the hydrometer in the tube and wait, the trub will drop out in 5 minutes or so.

 

[McKBrew]

The fact that you still had krausen (foam) indicates that your beer isn't done fermenting. If you took your sample just under the foam, and didn't stir up the bottom then the solids are all of the trub/yeast that hasn't settled out yet. Sometimes beer can take longer than a week, my IPA took 12 days before things started settling out.

In the future, if you see that much krausen, I wouldn't even bother to take a reading, it's not ready yet.

Edit: I missed the part about the autosiphon, you probably picked up some trub from the bottom as well. Get a wine thief as the Proffessor suggested.

Even so, you still have a few more days before you need to take another sample.

 

[southsidebrewer]

Thanks for the quick reply and advice. I'll pick up a theif from my LHBS.

southsidebrewer

 

[Joker]

I always let the krausen drop before taking any hydrometer readings.

 

[BierMuncher]

1) What are my alternatives to using the auto-siphon to remove the sample?
2) How concerned should I be with the solid trub material affecting my S.G. reading?

I always use a small, stainless steel pot. You can push the krausen away and take a decent dip for sampling.

I only use my racking cane when I’m sampling from a carboy.

Much easier to leave that autosiphon alone.

If you sample as I mentioned, trub won’t be an issue.

 

[dexter_craig]

I use a turkey baster. Sterilized of course. Is this ok?

 

[Grimsawyer]

I feel in my experience that watching the bubble lock is more important than checking the gravity of a beer. When the bubbling stops I wait a few days then get my keg ready then take my sample. A good amount of the time the beer is done. I did have a batch where the ferment got stuck at ~1.042 down from ~1.085. wasn't done, hehe. Don't be a slave to the hydrometer, it'll only make you worry. RDWAHAHB!!!! Use it more as a tool to measure the beer's alcohol than to check how far along it is. Remember, every batch acts differently. The best solution to 75% of brewing problems is just let it go wait a bit longer and the problem will work itself out on it's own. The thing about beer, and especially the one you are brewing (1.080 OG... yummy) give it time. Don't try to rush it. (I apologize if I upset anyone by this comment, but here goes...) From what I've experienced beer is very similar to women. It's ready when it decides it's ready and not a moment sooner. On the upside, if you wait for that moment you will be MUCH happier with it and it will be happier with you than if you try and hurry it along! Hope I have been some help!

 

[McKBrew]

I use a turkey baster. Sterilized of course. Is this ok?

That will work just fine.

 

[budbo]

I made a pipette out of a broken racking cane

 

[malkore]

The fact that you still had krausen (foam) indicates that your beer isn't done fermenting.

sorry but that's not 100% true. some strains of yeast are top cropping, and while the krausen does fall somewhat, you're still left with up to an inch of thick krausen 'skin' that protects the beer.
Wyeast Kolsch (2565) behaves like this..pretty strongly in fact.

its entirely possible the OP's beer isn't ready yet...maybe this is just his first FG test over the course of 3 days.

 

[Wables]

+1 on the turkey baster. It is probably my most used tool. I keep one sanitized to draw samples, top off air locks and fill and flush hoses with sanitizer. I haven't touched my thief in over a year.

 

[rabidgerbil]

I can't jump in on the turkey baster thing, because I use carboys, and that would never work. As to the comment about not worrying about the hydrometer reading, and simply watching the bubbler, I could not disagree with any comment more than I disagree with THAT comment. I don't even put a bubbler onto my beers unless they are conditioning in a secondary. As long as they are still fermenting, I simply use a blowoff tube. The only way to know for certain that a beer is done fermenting is to check the gravity. The bubbler simply can not tell you that. It is an airlock, not a scientific measuring device.

 

[jgln]

1) You can pick up a wine thief to take hydrometer readings (or use 50 ml pipettes from lab like I do ), it'll make things much easier.

2) I wouldn't worry too much about the trub, the hydrometer really is only affected by dissolved sugars. You can put the hydrometer in the tube and wait, the trub will drop out in 5 minutes or so.

Hopefully someone will see this, but doesn't a hydrometer really measure density? I mean I use a hydrometer to measure the amount of salt in my saltwater fish tank, not the sugar. So essentially any dissolved additive in a liquid can increase the specific gravity, right? If true dissolved starch (or whatever) from grains (like wheat/oats) would also add to it, correct? Assuming both statements are correct how can you figure out what your finishing gravity should be, assuming close to 0 being done? Obviously you can still figure out alcohol content based on the SG and FG but unless you have a way to calculate what to subtract away from sugars it would seem you would be lost. Just something I was thinking about after making a beer thick with adjuncts (right word?). The beer came out great but finished no where near 0.

 

[Cape Brewing]

As to the comment about not worrying about the hydrometer reading, and simply watching the bubbler, I could not disagree with any comment more than I disagree with THAT comment. I don't even put a bubbler onto my beers unless they are conditioning in a secondary. As long as they are still fermenting, I simply use a blowoff tube. The only way to know for certain that a beer is done fermenting is to check the gravity. The bubbler simply can not tell you that. It is an airlock, not a scientific measuring device.

I'll second that...

you could have absolutely zero activity in an air-lock for weeks and that doesn't mean anything in terms of fermentation being done. Obviously it's slowed but that doesn't mean it's done. The only way to really know if it's completely done is with a gravity reading.

 

[Cape Brewing]

Hopefully someone will see this, but doesn't a hydrometer really measure density? I mean I use a hydrometer to measure the amount of salt in my saltwater fish tank, not the sugar. So essentially any dissolved additive in a liquid can increase the specific gravity, right? If true dissolved starch (or whatever) from grains (like wheat/oats) would also add to it, correct? Assuming both statements are correct how can you figure out what your finishing gravity should be, assuming close to 0 being done? Obviously you can still figure out alcohol content based on the SG and FG but unless you have a way to calculate what to subtract away from sugars it would seem you would be lost. Just something I was thinking about after making a beer thick with adjuncts (right word?). The beer came out great but finished no where near 0.

Beer's don't finish near 0... they fluctuate dramatically depending on style. Some wheats, pale ales, etc will finish out in the low teens while something like a barleywine will finish muchmuch higher than that.

"0" is not a significant point on the hydrometer for any reason other than it's plain water at 60 degrees. Other than that, it has nothing to do with where a beer should finish.

And you shouldn't need to calculate anything in terms of where you should finish, any reasonably decent recipe should give you both an OG and a FG to shoot for.

 

[jgln]

Beer's don't finish near 0... they fluctuate dramatically depending on style. Some wheats, pale ales, etc will finish out in the low teens while something like a barleywine will finish muchmuch higher than that.

"0" is not a significant point on the hydrometer for any reason other than it's plain water at 60 degrees. Other than that, it has nothing to do with where a beer should finish.

And you shouldn't need to calculate anything in terms of where you should finish, any reasonably decent recipe should give you both an OG and a FG to shoot for.

I guess the answer I was looking for (agreement) was a hydrometer can't accuretly predict the available sugars in your wort unless you calculate exactly what you expect and use it as confiormation once fermentation is done. In other words the OG you have is not all fermentable sugars. So it's a two part step when using an new recipe to determine what sugars you have or will have available. Of course with a proven recipe you can use it to know if you made it right (OG) and once the FG is established you know when it should be finished. There has been discussion if are they needed or not (I think they are very useful) and it got me thinking that they only aid when knowing the FG if the recipe is proven, or you are one hell of an estimator on your new recipe. I guess now that I am experimenting more I realize it's difficult to use a hydrometer to know when the fermentation is done because I don't know what the FG will be until it's actually done. Thanks!

 

[Boston Brew Guy]

Rabidgerbill, did you even read the comment that you said you couldn't disagree more with? He said he doesn't take a hydro reading until the bubbles stop. There is nothing wrong with that. It waste less beer. He didn't say he didn't take reading ever.

 

[flyangler18]

He said he doesn't take a hydro reading until the bubbles stop. There is nothing wrong with that. It waste less beer. He didn't say he didn't take reading ever.

Except for the fact that relying on airlock activity (or lack of) is the brewing equivalent of a crapshoot. I've had plenty of fermentations that didn't bubble regularly- too many variables when looking at $1.50 piece of plastic.

That being said, I don't take a hydrometer reading anywhere before 14 days.

 

[jgln]

I guess the answer I was looking for (agreement) was a hydrometer can't accuretly predict the available sugars in your wort unless you calculate exactly what you expect and use it as confiormation once fermentation is done. In other words the OG you have is not all fermentable sugars. So it's a two part step when using an new recipe to determine what sugars you have or will have available. Of course with a proven recipe you can use it to know if you made it right (OG) and once the FG is established you know when it should be finished. There has been discussion if are they needed or not (I think they are very useful) and it got me thinking that they only aid when knowing the FG if the recipe is proven, or you are one hell of an estimator on your new recipe. I guess now that I am experimenting more I realize it's difficult to use a hydrometer to know when the fermentation is done because I don't know what the FG will be until it's actually done. Thanks!

After re-reading what I wrote please understand I am really talking about using a hydrometer to know when a beer is finished. With a new recipe that is difficult to do but the use of a hydrometer then is a good tool to make note of the OG/FG for the next time you brew that brew. I think I answered my own question. Unless soemone calls me an idiot I am done here

 

[flyangler18]

After re-reading what I wrote please understand I am really talking about using a hydrometer to know when a beer is finished. With a new recipe that is difficult to do but the use of a hydrometer then is a good tool to make note of the OG/FG for the next time you brew that brew. I think I answered my own question. Unless soemone calls me an idiot I am done here

If you are trying to calculate it long-hand, it can definitely be difficult- but it's doable. I rely on my brewing software. Malts and other grain have different sugar concentrations and potential for extraction. Your brewing software will use these figures to estimate an SG for a recipe based on the specific grain used.