Gravity of fermenting wort?

[Kyled93]

Ok guys,

Have a really quick question. My starting gravity was 1.055 when I pitched my S-04 last Saturday. It's been 6 days so I decided to pull a sample and got a measurement of 7.20 brix. Now according to beersmith, my adjusted gravity should be 1.011 which would mean I'm near the end of fermentation. Does this adjusted number sound correct? It just seems off for some reason. I was thinking of cold crashing tomorrow but I'm not sure. Any suggestions?

 

[MalFet]

7.2 brix on your refractometer? There's a wide margin of error on post-fermentation refractometer readings, so 1.011 ±5 points sounds about right. If that's 7.2 on a hydrometer, though, wouldn't be 1.011. Can you take a new measurement with a hydrometer?

 

[Kyled93]

7.2 brix on your refractometer? There's a wide margin of error on post-fermentation refractometer readings, so 1.011 ±5 points sounds about right. If that's 7.2 on a hydrometer, though, wouldn't be 1.011. Can you take a new measurement with a hydrometer?

Yea 7.2 on my refractometer. Why is there that much margin of error?

I'll try to get a new reading on a hydrometer this weekend. Mine broke so I have to go pick up one at my LHB.

Even with the margin of error, beersmith estimated my FG to be 1.014. Should I wait to crash or crag this weekend?

 

[duboman]

Even with conversion calculators refractometers are pretty worthless post fermentation, get a replacement hydrometer and take a new reading. Most likely after 6 days the beer probably is pretty close to being done but you should leave it another week or two to clean up and clear anyways.

 

[MalFet]

Yea 7.2 on my refractometer. Why is there that much margin of error?

I'll try to get a new reading on a hydrometer this weekend. Mine broke so I have to go pick up one at my LHB.

Even with the margin of error, beersmith estimated my FG to be 1.014. Should I wait to crash or crag this weekend?

Refractometers were designed to measure the refractive index of pure sucrose solutions, which is directly related to the concentration of solute. The wort we brew is made up of a wide range of different sugars, and thus the measurement needs to average a number of different variables. When we throw alcohol into the mix, it gets even more complicated. In other words, there is no way to know how to calibrate a refractometer without knowing the exact composition of your wort/beer, which of course we don't.

Anyway, your current gravity is not 7.2 brix...that's just the reading you get before applying estimated corrections. The reading taken by a hydrometer would probably be somewhere near 3 or so.

There's no way for me to guess if it's done from here, but if you take another reading in 48 hours and it's still at the same value that's a pretty good indication.

 

[MalFet]

Even with conversion calculators refractometers are pretty worthless post fermentation, get a replacement hydrometer and take a new reading. Most likely after 6 days the beer probably is pretty close to being done but you should leave it another week or two to clean up and clear anyways.

I certainly wouldn't call them worthless, but you definitely need to understand their limitations.

Anyway, to the OP, for more technical details check out this thread:
https://www.homebrewtalk.com/f36/refractometer-question-362437/

 

[duboman]

I certainly wouldn't call them worthless, but you definitely need to understand their limitations.

Anyway, to the OP, for more technical details check out this thread:
https://www.homebrewtalk.com/f36/refractometer-question-362437/

Perhaps not worthless, too strong a word but as you stated, without a full understanding of their limitations, hydrometers, IMO are a much more reliable tool post fermentation

 

[Kyled93]

Well took my reading tonight and it was at 1.021.. I'll be waiting a few more days to make sure I hit my mark be for I crash.

Thanks guys!

 

[Kyled93]

So I took few more readings and it seems to be stopped at 1.018. That being said, if I mashed in at 154-156 would/could this cause the gravity to stay at 1.018?

 

[Yooper]

So I took few more readings and it seems to be stopped at 1.018. That being said, if I mashed in at 154-156 would/could this cause the gravity to stay at 1.018?

Yes, depending on the ingredients.

 

[Kyled93]

Yes, depending on the ingredients.

Hum....

Here is my grist:

17 lbs Pale Malt (2 Row) US (2.0 SRM)
1 lbs 8.0 oz. Flaked oats
1 lbs 8.0 oz Caramel Malt - 60L (Cargill) (60.0 SRM)
16.0 oz Chocolate Malt (350.0 SRM)
4.8 oz Special B Malt (180.0 SRM)
16.0 oz White Wheat Malt (2.4 SRM)
2.0 oz Willamette [7.50 %] - Boil 60.0 min
1.0 oz Willamette [7.50 %] - Boil 30.0 min
2.0 oz Willamette [7.50 %] - Boil 5.0 min
1.0 pkg Safe ale-S04
1.00 Items Vanilla Beans (Secondary)

What do you think Yooper? Possible?

 

[Yooper]

Hum....

Here is my grist:

17 lbs Pale Malt (2 Row) US (2.0 SRM)
1 lbs 8.0 oz. Flaked oats
1 lbs 8.0 oz Caramel Malt - 60L (Cargill) (60.0 SRM)
16.0 oz Chocolate Malt (350.0 SRM)
4.8 oz Special B Malt (180.0 SRM)
16.0 oz White Wheat Malt (2.4 SRM)
2.0 oz Willamette [7.50 %] - Boil 60.0 min
1.0 oz Willamette [7.50 %] - Boil 30.0 min
2.0 oz Willamette [7.50 %] - Boil 5.0 min
1.0 pkg Safe ale-S04
1.00 Items Vanilla Beans (Secondary)

What do you think Yooper? Possible?

Yes, with those ingredients and mashing at 156, I think 1.018 is a reasonable FG.

 

[Kyled93]

Thanks for the help!

I am still fine tuning my system and was aiming for 154. I guess when it floated to 156, for 30 mins or so, this is what is causing the 1.018 to be FG.