Basic Hydrometer question

[HB_in_Subic]

I have just now started to pay attention to SG. I put my triple scale hydrometer in a calibrated cylinder and it measured at 1.0 in 84F tap water. The graduation scale in the paperwork says add .003 at 84F.

So I measured my latest batch of wort (pre-yeast pitch) at 1.053 (84F). So would that make my SG at 1.056 or 1.051?

Thanks for entertaining this basic noobie question.......

 

[petey_c]

1.056

 

[HB_in_Subic]

Thanks for the quick reply. It is much appreciated. I am starting to document my brews more closely now that I have my processes good. I am not getting anal but want to eliminate some of the guess work (when to bottle vs. letting it sit for 3 weeks). I am also going to use the readings to QC my target OG.

 

[Conan]

Did the hydrometer specify 84 degree water as a calibration? They're typically set at 60*F. I'll automatically add about .002-3 to the reading if it's taken in the 80*F range.

Just re-read your question...it sounds like it's calibrated at 84. And as Petey said you'd adjust to 1.056. Kyle

 

[unionrdr]

Yeah, the red flag went up in my mind too. Mine calibrates at 60F. I guess there's some out there that are more different in that regard?

 

[HB_in_Subic]

It is calibrated at 60F and the adjustment at 84F is .003 ...

Too much beer tonight translates to lackluster clarification of my original post...

 

[unionrdr]

Ah,OK. Here's a calculator I use for quickie adjustments; http://www.brewheads.com/gravcorrect.php

 

[peterj]

Wait, why are you measuring everything at 84F? And if the hydrometer read 1.000 at 84F then it is not calibrated correctly. If it's calibrated at 60F then it should read 1.000 at 60F and 0.997 at 84F with water in it. If it read 1.000 at 84F then your reading of 1.053 for your wort at 84F would be the correct gravity.

 

[jsprinceiii]

Wait, why are you measuring everything at 84F? And if the hydrometer read 1.000 at 84F then it is not calibrated correctly. If it's calibrated at 60F then it should read 1.000 at 60F and 0.997 at 84F with water in it. If it read 1.000 at 84F then your reading of 1.053 for your wort at 84F would be the correct gravity.

You have that backwards.
The adjustment would add, not subtract.

 

[soccerguy83]

1.050

If it should be 1.000 at 60F, and it was 1.000 at 84F in water, then it is reading 0.003 high (if calibrated correctly should have read 0.997 in water at 84F according to the documentation in your manual). So you actually need to subtract 0.003 from your wort reading at 84F.

 

[unionrdr]

Good point. That's what got me to wondering about the readings.

 

[bernardsmith]

I agree with peterj. Something is not right here. Typically, liquids become less dense the higher the temperature. Think of the difference between ice and steam... The nominal density of pure water at 60 degrees is 1.000 - if 60 degrees F is the temperature at which your hydrometer is calibrated. Water at 84 F should be less dense and so should give you a reading below 1.000 (alcohol is less dense than water which is why a mixture of water and alcohol when you make wine ought to give a reading below 1.000 when all the sugars in fruit have fermented out) - .. I would recheck your hydrometer reading with cooler (60 F) water.

But if the hydrometer is correctly calibrated, a reading of 1.050, say at 84*F is the same as a reading of 1.053 at 60*F - you need to ADD 3 points to compensate for the higher temperature , not subtract them. The same wort will be more dense at the lower temp than it is at the higher temp.

 

[jsprinceiii]

Re-read the post...
That is correct, subtract.. Ignore my prior comment!!

 

[peterj]

You have that backwards.
The adjustment would add, not subtract.

No, if it was actually calibrated to 60F and water reads 0.997 at 84F then you would add 0.003 and it would be 1.000. So it should read 0.997 with water at 84F if it was correctly calibrated (which it sounds like it's not).

EDIT: I posted this before I saw you're retraction jsprinceiii!

1.051

If it should be 1.000 at 60F, and it was 1.000 at 84F in water, then it is reading 0.003 high (if calibrated correctly should have read 0.997 in water at 84F according to the documentation in your manual). So you actually need to subtract 0.003 from your wort reading at 84F.

No, if it's reading 1.000 at 84F then it's actually calibrated (miscalibrated really) to 84F. So a wort measurement taken at 84F would not need to be corrected.

 

[Gavin C]

A better way is to check the reading in a sample at the correct temperature. Just cool the sample in the fridge/ice batch till it reaches the calibration temperature written on the hydrometer. Most are 60 or 68F. A small sample cools to the desired temp very quickly.

If you do this you entirely eliminate any confusion and external variables other than altitude which is usually negligible.

 

[soccerguy83]

No, if it's reading 1.000 at 84F then it's actually calibrated (miscalibrated really) to 84F. So a wort measurement taken at 84F would not need to be corrected.

haha I'm an idiot and over thought the issue prior to finishing my morning coffee. You are 100% correct!

 

[peterj]

A better way is to check the reading in a sample at the correct temperature. Just cool the sample in the fridge/ice batch till it reaches the calibration temperature written on the hydrometer. Most are 60 or 68F. A small sample cools to the desired temp very quickly.

If you do this you entirely eliminate any confusion and external variables other than altitude which is usually negligible.

Yeah, I would take a reading with plain water at 60F to confirm if the calibration is off.

 

[bacgabe]

Thanks for entertaining this basic noobie question.......

See, not such a noobie question after all.

 

[Conan]

Yeah, I would take a reading with plain water at 60F to confirm if the calibration is off.

Not to be a jerk, but wouldn't distilled water at 60F be best?
(Pound sign)poking the bear. Kyle

 

[HB_in_Subic]

OK... I just used 60F tap water to test the calibration. My hydrometer is off, it reads 1.02 at 60F.

Any recommendations for determining my offset for future readings?

I am guessing that I would add this difference from the calibrated level (.02) plus the normal additions by temperature. So for my reading of 1.052 at 84F, the adjusted reading would be 1.057.

 

[imasickboy]

Distilled water is the correct way to test calibration.

 

[HB_in_Subic]

Alright, I will try to find some distilled water.

 

[HB_in_Subic]

Found some distilled water and it gave the proper reading at 60F. So... my OG on my latest batch was 1.052+.003 (@84F) = 1.055 for my Pacific Saison

Thanks for everybody's input

 

[peterj]

Not to be a jerk, but wouldn't distilled water at 60F be best?
(Pound sign)poking the bear. Kyle

OK... I just used 60F tap water to test the calibration. My hydrometer is off, it reads 1.02 at 60F.

Any recommendations for determining my offset for future readings?

I am guessing that I would add this difference from the calibrated level (.02) plus the normal additions by temperature. So for my reading of 1.052 at 84F, the adjusted reading would be 1.057.

Found some distilled water and it gave the proper reading at 60F. So... my OG on my latest batch was 1.052+.003 (@84F) = 1.055 for my Pacific Saison

Thanks for everybody's input

Yeah, that's true distilled water is technically the way to do it. I didn't think there would be that much of a difference though. Guess I was wrong!

Though, thinking about it, if you're brewing with tap water wouldn't you want your hydrometer calibrated to your tap water....? I've never really thought about that.

 

[unionrdr]

I've used tap water when I was still brewing with that. Then spring & distilled. Not much if any difference.