Hydrometer correction...is the Brew Your Own website correct?

I just bought a new hydrometer yesterday and was getting some strange readings. Well I just checked it with distilled water at 70F and itis reading 0.984. With distilled water it should read 1.000. That is a big difference!

It says at BYO web site Brew Your Own: The How-To Homebrew Beer Magazine - Projects and Equipment - Calibrate Your Hydrometer and Fermenter: Techniques that I should, since I am low on my gravity reading, subtract the difference(in my case .16) from the reading that shows on the hyrdometer.

It says that in the 4th paragraph down under "Single point calibration"

I would think that I would have to add .16 to any reading that I read.

Who is right? I am brewing in about a half hour so any quick help would be appreciated.

I'm confused - what temperature is your hydrometer calibrated for? 60° or 68°. This will make a difference.

Oy...now my head hurts. Distilled water at the calibration point should have a reading of 1.0, right?

So if your hydrometer reads 0.984 at 10 F, shouldn't you add 0.016 to that to bring yourself to 1? I think the article is backwards, unless I'm completely oblivious as to what a hydrometer is doing.

MMW said:

Oy...now my head hurts. Distilled water at the calibration point should have a reading of 1.0, right?

So if your hydrometer reads 0.984 at 10 F, shouldn't you add 0.016 to that to bring yourself to 1? I think the article is backwards, unless I'm completely oblivious as to what a hydrometer is doing.

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That's what I think. I need to ADD the .16.

It is calibrated for 60F

I added 1 to the reading since I am calibrating at 70F

Example: I am reading .983, then add 1 for the 70f, so I come out with .984

oops...that should be 70 F. Probably hard to take a reading of DW at 10 F :cross:

maybe I'm over thinking this, but I always feel much safer using ratios when making corrections like this, rather than just adding .16

So 1/.984 = SGc/SG

or

1.017 x observed SG = corrected SG.

BrewCalcs: Free Homebrewing Calculations has an easy SG temperature calibration.

You need to subtract it. Think of it this way: 0.984 is your hydrometer's 1.000.

From the article linked above:

If you’re lucky, your hydrometer reads 1.000 at the specified temperature. If it reads either higher (1.001 or more) or lower (0.9999 or less), simply add or subtract the amount of error from your readings in wort or beer. For example, let’s say your hydrometer reads 0.998 in pure water at 60 °C (its calibration temperature). This means that it’s reading two “points” low and you should subtract two “points” from any reading you take in wort or beer. In other words, if your wort reads 1.050, your corrected reading would be 1.048.

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This sure seems bass-ackwards to me. I would add 2 points to the measured value in the above case. So it should be 1.052 in the example above.

double_e5 said:

You need to subtract it. Think of it this way: 0.984 is your hydrometer's 1.000.

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So, the other day I take a reading of my Centennial Blonde at it reads 0.983. You and the BYO web site say I should subtract it.

That means that my reading was actually 0.967.

It just doesn't fugure. Then again I have been called a simpleton.

It means it was 0.999. Which means you are having more problems then your hydrometer reading low.

And now I'm confused as hell.

I think what the article and myself are saying is to take your reading and subtract what your 1.000 reading is in distilled water (i.e. 0.984).

So if your SG is 1.050:

1.050 - 0.984 = .066 or 66 points.

Which is the same thing as 1.050 + .016.

With my explanation, just add the damn thing.:cross: That article is confusing as hell.

Unless you have a scientific hydrometer, you're not reading the hydrometer correctly. They don't even go below .990. You may be reading .9984, though. Can you post a picture, or a link, to your hydrometer?

double_e5 said:

It means it was 0.999. Which means you are having more problems then your hydrometer reading low.

And now I'm confused as hell.

I think what the article and myself are saying is to take your reading and subtract what your 1.000 reading is in distilled water (i.e. 0.984).

So if your SG is 1.050:

1.050 - 0.984 = .066 or 66 points.

Which is the same thing as 1.050 + .016.

With my explanation, just add the damn thing.:cross: That article is confusing as hell.

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I did have a lot of problems with my first all grain. The 0.999 is a sure sign that it was as bad as I thought it was going to be.

YooperBrew said:

Unless you have a scientific hydrometer, you're not reading the hydrometer correctly. They don't even go below .990. You may be reading .9984, though. Can you post a picture, or a link, to your hydrometer?

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The hydrometer reading was off the chart. I just guessed what it would be by looking at the distance from lets say 1.000 to 0.990. My best guess is that it was 0.983. I will take a photo of it in a little while and you guys can see for yourself.

Ok, here are the pics.

The 1st one is of distilled water @70f

The 2nd is of my Centennial Blonde @ 70F

Try adding water almost all the way to the top, and spin it a little. Maybe it's not floating? It's hard to tell.

If it's really floating like that, it looks like the slip of paper inside has slipped down. It's really not usable like that. You can adjust a reading, but that reading isn't even close and/or accurate.

YooperBrew said:

Try adding water almost all the way to the top, and spin it a little. Maybe it's not floating? It's hard to tell.

If it's really floating like that, it looks like the slip of paper inside has slipped down. It's really not usable like that. You can adjust a reading, but that reading isn't even close and/or accurate.

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I have spun it and it is floating. I will bring it back to the brew store on Saturday.

BTW, like your avatar. Yooper huh. My best friend of 20 years is from Harvey, which is just outside of Marquette. She still has family up there.