well after a week of fermenting i did a check on gravity and i am getting 2 different results, hydro is telling me it is at 1.013 and refracto is saying 1.025 i wonder which is right, i also wonder why two different readings? thanks in advance.
Hydrometer or refractometer
- Thread starter busa504
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- Thread Starter
- #4
it taste done to me, more dry than sweet. but why the 2 different readings?
- Thread Starter
- #5
i have the atc brew fractometer, so which one is correct?? or how do i adjust?
Once there is alcohol in a solution, the refractometer is inaccurate. There are conversion tables on the internet or in brewing software, but my experience is that they are never really accurate.
A refractometer is great for pre-fermentation readings, and a hydrometer is great for post fermentation readings. The hydrometer would be correct in this instance, since it's post fermentation.
A hydrometer measures specific gravity directly, while a refractometer infers it from the refractive index of the solution, making the assumption that the major component of the solution is sugar. When that is not the case (as in alcohol-containing solutions) a refractometer is not accurate.
There are a lot of different equations and calculators that will give you an ESTIMATE of gravity from a post-fermentation refractometer reading. Some are better than others; my favorite is here:
http://seanterrill.com/2012/01/06/refractometer-calculator/
But these are just estimates, and will likely be off of the true gravity by a few points. A good low-gravity hydrometer (one that reads from 0.990 to 1.020) is the most accurate way to go.
- Thread Starter
- #8
thank you for clearing that up, we learn something new everyday thanks again.
- Thread Starter
- #9
now that you have sent this link, the refract would be corrected saying 1.010 instead of the 1.025, which is very close to the hydro reading at 1.012. thanks for the help guys.
hoptualBrew
Well-Known Member
Hydrometer never fails! Refractometer before fermentation, hydrometer after it starts and alcohol is in solution.
Although I have yet to be off on post fermentation refractometer readings, many others have.
I use it for a quick check to see if it's close to done or even going good.
However, once the beer is fermented, and at room temperature, it's ALMOST as easy to take a hydro reading, and you also get to taste a wort sample, so using the refractometer at that point is nearly useless IMO. The real benefit of a refractometer is during the actual brewing because it allows you to take a quick reading and adjust the brew as needed without waiting for a large sample to cool down. I usually have 60 degree water sitting in a glass and swirl the pipette bulb around to get it to readign temp. Takes a few seconds and you are ready to go.
I use it for a quick check to see if it's close to done or even going good.
However, once the beer is fermented, and at room temperature, it's ALMOST as easy to take a hydro reading, and you also get to taste a wort sample, so using the refractometer at that point is nearly useless IMO. The real benefit of a refractometer is during the actual brewing because it allows you to take a quick reading and adjust the brew as needed without waiting for a large sample to cool down. I usually have 60 degree water sitting in a glass and swirl the pipette bulb around to get it to readign temp. Takes a few seconds and you are ready to go.
iaefebs
Banned
When I googled Brew fractometer the one I saw listed measured in Brix. From your 1st post you gave a measurement in SG. I'm going to guess that you did the conversion yourself to show 1.025
What were your readings in Brix Starting and ending.
I'm going to guess that with 75% attenuation, your initial reading was 12.2Brix with a final of 6.4brix. Converted to SG that would be a 1.048 start with a 1.012 finish.
Am I close?
BTW after taking many comparative readings I don't bother using the hydrometer anymore.
jbsengineer
Well-Known Member
I have been mirroring my refractometer and hydrometer readings pre and post fermentation for the last 4 batches. I have found the refractometer consistently reads .001 low so I have compensated for that. However it has been very consistent. I'm using Beersmith for the calculations of brix and unfermented vs. fermented wort.
If the readings keep consistent like this, I might only break out the hydrometer once in a while to verify the refractometer is still performing accurately.
I have a digital refractometer by the way.
If the readings keep consistent like this, I might only break out the hydrometer once in a while to verify the refractometer is still performing accurately.
I have a digital refractometer by the way.
william_shakes_beer
Well-Known Member
You can get a dual scale refractometer that shows both readings side by side.When I googled Brew fractometer the one I saw listed measured in Brix. From your 1st post you gave a measurement in SG. I'm going to guess that you did the conversion yourself to show 1.025
What were your readings in Brix Starting and ending.
I'm going to guess that with 75% attenuation, your initial reading was 12.2Brix with a final of 6.4brix. Converted to SG that would be a 1.048 start with a 1.012 finish.
Am I close?
BTW after taking many comparative readings I don't bother using the hydrometer anymore.
- Thread Starter
- #15
thats the one i am using... my og was 1.053 or about 13.5 brix when i measure a week later i am grtting 1.025 or 6.2 brix... hydro says 1.012 so we are close.
i use a hydrometer to take preboil gravity since i can pour it back into the BK w/o worrying about contamination.. other than that i only use my refrac now.. after doing a couple batches using both and comparing them i much prefer to use the calculations and not waste a couple of ounces each time.. i've never been a good judge of how a beer is going to taste until it is chilled/carbonated so i don't bother tasting too much anymore.. with the refrac all i can suggest is just to drop the sample in, then wait a good 30-60 sec before you look at it and the line will be much more clearer due to the temperature fix
iaefebs
Banned
Using a conversion with your Brix readings shows a 1.007 Final. That gave you 86% attenuation. What yeast did you use US-05?
- Thread Starter
- #18
i used wlp001 california ale, made a 2L starter with stir plate.
iaefebs
Banned
That's above the expected attenuation for that yeast, but.... anything can happen. What I often see when people read either a Hydrometer or Refractometer, is that they want to hit their goals, so they might see a higher OG than someone impartial might, and may see a slightly lower FG if needed. I'm not saying that this may have happened in your case, but it does happen with both measuring devices.
- Thread Starter
- #20
i just checked my hydrometer again and its at 1.010 down from og of 1.053 the refrac seems to stay at 1.025That's above the expected attenuation for that yeast, but.... anything can happen. What I often see when people read either a Hydrometer or Refractometer, is that they want to hit their goals, so they might see a higher OG than someone impartial might, and may see a slightly lower FG if needed. I'm not saying that this may have happened in your case, but it does happen with both measuring devices.
iaefebs
Banned
I'm getting a little confused. When you shuffle between refractometer readings in Specific Gravity, or Brix. What scale do you have on your refractometer? If you have a scale that reads in SG, you are never going to get an accurate reading. If you have a dual scale SG/Brix completly ignore the SG reading. What did you use for your OG reading of 1.053?
- Thread Starter
- #22
for the og i used the refrac sg scale, the refrac has sg/brix
iaefebs
Banned
For final Gravity completely ignore the Specific Gravity scale.I don't believe A decent refractometer should ever have a SG scale. These were designed to be sold to people that wanted to have a scale that matched a hydrometer because the numbers were familiar to homebrewers. This is not a linear measurement during ferment and I think it is what causes all this confusion. When you add the "sucrose" argument and the "not accurate to .003" while ignoring the users interpretation of a reading.
