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Brews & Views Bulletin Board Service * Brews and Views Archive 2005 * Archive through January 29, 2005 * Hydrometer Adjustments < Previous Next >

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Mike Huss
Intermediate Member
Username: Mikhu

Post Number: 399
Registered: 03-2003
Posted on Friday, January 21, 2005 - 07:33 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

So I figured out that my stupid hydrometer is bad. The good news is my efficiency isn't as bad as I thought and I can stop wondering why my FG's are coming out so low.

When I checked it in 60 deg distilled water it gave me a .992 reading. Question is, is that error off in a linear fashion vs temp? In other words, can I assume for my last batch where my FG was 1.004, is that really 1.012? And as for temp, what about my OG after the mash? Do I just add those 8 points no matter the temp?

I'm really just wondering what the true numbers were for this last batch so I can get a better idea on my efficiency. I plan on replacing that piece-o-crap before I brew again.
 

Bill Pierce
Moderator
Username: Billpierce

Post Number: 1936
Registered: 01-2002
Posted on Friday, January 21, 2005 - 07:38 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

There was an article in Zymurgy a few years back about making reference sugar solutions for hydrometer calibration. I'll see if I can find the issue.
 

Rob Farrell
Member
Username: Robf

Post Number: 232
Registered: 02-2003
Posted on Saturday, January 22, 2005 - 02:17 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

The error is linear. If your hydometer is calibrated at 60 F, then just add 0.008 to your readings. Apply temperature correction (which is not linear) to the corrected reading.
 

Mike Huss
Intermediate Member
Username: Mikhu

Post Number: 402
Registered: 03-2003
Posted on Saturday, January 22, 2005 - 03:24 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Thanks guys!
 

Richard Nye
Advanced Member
Username: Yeasty_boy

Post Number: 509
Registered: 01-2004
Posted on Saturday, January 22, 2005 - 11:34 am:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Mike and Rob, not so fast. I have (had) a hydrometer that was off by 5% over the whole range! In fact, it read 0 when I put in 6oF water. But at 1.050 it read 1.055. The only way I can explain it is the paper inside the hydrometer (with the scale on it) may have been reduced during a photocopying process. I just bought 3 narrow range hydrometers then a refractometer. Those more accurate instruments cleared up a lot of questions I had about my brewing.
 

Richard Nye
Advanced Member
Username: Yeasty_boy

Post Number: 510
Registered: 01-2004
Posted on Saturday, January 22, 2005 - 12:26 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Oh, the other half of that post is I discovered this by making some sucrose solutions that Bill mentioned. A 10 degree Plato solution (1.040 S.G.) is 10% sucrose by weight and 90% water. Mix up the solution (making sure all of the sugar dissolves), measure this with your hydrometer and see what you get (after temperature corrections).

20 degree Plato = 1.083 = 20% sucrose by weight

Here's a good article to read from Brewing Techniques:

http://www.brewingtechniques.com/library/backissues/issue1.3/manning.html
 

Bill Pierce
Moderator
Username: Billpierce

Post Number: 1947
Registered: 01-2002
Posted on Saturday, January 22, 2005 - 02:04 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Thanks, Richard. When preparing solutions for hydrometer calibration, measure the sugar very accurately by weight, within 1 gram. And if possible measure the water volume to the nearest milliliter.
 

Rob Farrell
Member
Username: Robf

Post Number: 233
Registered: 02-2003
Posted on Saturday, January 22, 2005 - 03:50 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

I had assumed the paper had slipped or the weight was off. I should have stated that. You know what they say about assuming.
 

Richard Nye
Advanced Member
Username: Yeasty_boy

Post Number: 514
Registered: 01-2004
Posted on Saturday, January 22, 2005 - 06:03 pm:   Edit Post Delete Post View Post/Check IP    Ban Poster IP (Moderator/Admin only)

Rob, that's probably what happened, but maybe not. Better to check.