Is my hydrometer accurate

I went to use my hydrometer the other day, and I'm not sure it is accurate. After I looked at it, it is a hollow glass tube with a rolled up piece of paper in it with a Tralle and Proof scale lines on it. The paper inside is not resting on the bottom, it is floating in the middle of the glass tube. Is this normal?

Well there is a tolerance to it's accuracy. But you can check the scale by putting distilled water in the sample tube. Water should read a SG of 1.000.

If the scale is off by a couple hundreths it's common. Just note the difference and add/subtract from subsequent readings.

Also, to ensure accuracy use a thermometer when you take your reading. There is a correction for tempurature. best bet is to ensure that the sample being tested is at the hydrometers rated temp. Usually 68*F. that should be clarified in the paper with the hydrometer or noted on the inner scale.

I thought most Hyddrometer's where actually clocked in at 60F? I may be wrong, in the end it will always be better to look on the paper for your specific setting.

Yeah I finally discovered that my hydro is way off. Like water reads 1.004 or some foolishness. I just use it as a relative measure for my own brews.

Well, part of my problem with it is that the space between reading lins is so small i don't know how you read fractions between each line.

Frenchy said:

Well, part of my problem with it is that the space between reading lins is so small i don't know how you read fractions between each line.

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Well, each line is .002, so the fraction doesn't matter to me at all.

If it's at one line, for example, the reading may be 1.054. The next line is 1.052. I'm happy with knowing halfway between is 1.053, and I don't need to be more accurate than that.

I have to add 4 points to each reading I get. It sucked as it took me 3 batches to figure that out. As Gila stated measure it with 60F DI water and this gives you the correction factor for all other readings.

and I forget - do you read from top of meniscus or bottom?

Top of the meniscus, I'm pretty sure.

im gonna have to disagree and say bottom of a meniscus. I'm sitting next to a chemist, sorry dude

jamesnsw said:

Top of the meniscus, I'm pretty sure.

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yes, just read the directions.

Frenchy said:

with a Tralle and Proof scale lines on it.

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You sure thats not an alcohol hydrometer? Does it also have a scale for SG?

my science teacher always told me bottom of meniscus for sciency stuff, but this could be different.

That's why I said I'm pretty sure.

Never listen to the Comm grad on sciency things

jaginger said:

my science teacher always told me bottom of meniscus for sciency stuff, but this could be different.

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jamesnsw said:

That's why I said I'm pretty sure.

Never listen to the Comm grad on sciency things

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yeah, my science background says the same thing, but my hydro instruction sheet says to read from the top of the meniscus (too lazy to post a pic)

from what i recall, its the bottom of the meniscus unless its something like mercury which has an inverted meniscus.

Honestly with the difference between the top and bottom being about .002, arguing over which one is correct is the height of lab *****ebaggery.

No, it doesnt' have a scale for SG. I just checked my hydrometer, and it read 0, in my tap water. But then I put a teaspoon of sugar into the water, and the hydrometer read below 0 (not even on the scale)

You probably need a new brewing hydrometer. I don't know of the differences between distiller's hydrometer, and salt water aquarium hydrometers, etc, but a new brewing hydrometer with the SG scale is about $7 or so and it's worth it!

The instructions for my hydrometer are to read from the TOP of the meniscus. I'm sure different manufacturers can set the scale to read from either the top or the bottom of the meniscus so read the instructions. I think reading from the top meniscus makes it slightly more easy with very dark beers that are rather opaque.

In the end reading it the same way each time is the most important thing except when you are trying to calculate efficiency.

Bobby_M said:

Honestly with the difference between the top and bottom being about .002, arguing over which one is correct is the height of lab *****ebaggery.

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unless you're inconsistent and you measure your OG from the top and your FG from the bottom

AZ_IPA said:

unless you're inconsistent and you measure your OG from the top and your FG from the bottom

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Yup. That way you can brag about high efficiency AND high attenuation!

Ok, I'm not sure exactly what I was originally sold. But the first "hydrometer" I was sold had Zero at the very bottom, and the scale increased as it went up the hydrometer. I took this back, and got a correct hydrometer. The Zero was at the top of the cylinder, and the scale increased as it went down the hydrometer. I thought there was something off about that other item. I'm not exactly sure what it was.