Is there such a thing as a malfunctioning (or inaccurate) hydrometer? Has anyone ever had a “faulty” hydrometer.
I have read the basic guidelines about taking readings, and it seems pretty simple. Does anyone have a tried and true gravity reading schedule that works well? (times, temps, etc.) Thanks!
Hmmmm, not really sure what you are asking.
Hydrometers are not exact and vary quite a bit. Best to check them in regular water where they should read 1.000 (I think?)
Lots of tricks to correct ones that are reading too high, such as adding nail polish to add a bit of weight.
“Does anyone have a tried and true gravity reading schedule that works well? (times, temps, etc.)”
This is what I am not sure what you are asking. I measure OG when I pitch the yeast. I almost never check again until at least 2 weeks are up, generally 3. I then either transfer to secondary or keg. I might check again if I transfer from secondary to keg, but generally don’t.
Are you wanting to check more often than that?
I recommend checking gravity before starting the boil, several times during the boil, and at the end of the boil so you can adjust the gravity by adding water or boiling more vigorously and longer. All the sampling during the boil is because I’m try to hit a pre-determined SG: I let the volume fall where it may.
Starting about two weeks into primary fermentation, check gravity every couple of days so you know when fermentation is complete.
When taking your gravity readings remember that measured specific gravity decreases as a substance heats and increases as it cools - water breaks the rule between about +4 and 0 C, but that’s just so physicists have a job. That means you must either heat or cool your sample to whatever temperature your hydrometer is calibrated for - 59 F (15 C) in my experience - or you must use a correction table. I’ve not been impressed by my ability to use correction tables. A small error reading the specific gravity of a hot sample seems to translate into a large error in the “corrected” reading. I prefer cooling the sample to about 59 F. This is more important when checking to confirm fermentation is complete than during the boil.
That may seem like a lot of sampling and, as you may have noticed, it is not a part of the Laws of Home Beer Making. I’m pretty casual about obeying “The Laws”; I just happen to be more concerned with hitting my target gravity than most other aspects of the hobby. Relax, have a home brew, and check your gravity as often as seems right to you.
Assuming you’re brewing extract-only and can follow a recipe, measure water accurately, and have your fermenter marked for the proper volume, you don’t need to take any readings prior to pitching the yeast (because your OG will be what’s predicted by the recipe). After 2-3 weeks, take a reading, wait 2-3 days and take another, and if they match and you’re happy with the FG, leave it for another week and then bottle. If the gravity is too high, rouse the yeast and increase the temp a couple degrees to get the yeast back into action, and take another gravity reading in a week.
Once you move to partial-mash or all-grain, gravity readings are much more important throughout the process. If you intend to go down this path, you might want to invest in a refractometer now and make gravity readings easier with less loss of wort/beer.
I have a faulty hydrometer. It reads 0.003 too high, which needs to be subtracted every time I use it. And how do I know this? Measure the gravity of plain cool water. If this reads 1.003, it is obviously reading too high! But that doesn’t make the hydrometer worthless. It just needs the readings adjusted. This sort of test is essential for every homebrewer who is concerned about the accuracy of their hydrometer.
Also key with any hydrometer reading is the temperature. Try to always measure at about 60 F for the greatest accuracy. I agree that the commonly used temperature adjustment tables seem to be a little off. You need to measure with the temperature in the 60s (i.e., the ideal fermentation temperature for most ales) whenever possible.
Thanks for the advice. I have been fly sparging and taking a reading of the first runnings, at pre-boil, and at flame out…I am not too concerned with measuring gravity until racking to the secondary. Ultimately, I think my reading temperature on the last batch was too hot…My recipe called for an OG of 1.052 and I was reading about 1.030 pre-boil…
I think my biggest problem is not letting the wort cool to 60 degrees…anyway, Thanks again for the advice.
[quote=“Brandonscott79”]I am not too concerned with measuring gravity until racking to the secondary.[/quote]This sounds suspiciously like you’re taking a reading as you rack to secondary on a specific schedule rather than taking a reading and then deciding that it’s time to rack. 
Good observation…never thought of it that way before…
Patience is one of the hardest things to learn in homebrewing (if you don’t already have it). Let the yeast make the schedule rather than the other way around and you’ll likely see a marked improvement in your beer.
[quote=“dmtaylo2”]I have a faulty hydrometer. It reads 0.003 too high, which needs to be subtracted every time I use it. And how do I know this? Measure the gravity of plain cool water. If this reads 1.003, it is obviously reading too high! But that doesn’t make the hydrometer worthless. It just needs the readings adjusted. This sort of test is essential for every homebrewer who is concerned about the accuracy of their hydrometer.
Also key with any hydrometer reading is the temperature. Try to always measure at about 60 F for the greatest accuracy. I agree that the commonly used temperature adjustment tables seem to be a little off. You need to measure with the temperature in the 60s (i.e., the ideal fermentation temperature for most ales) whenever possible.[/quote]
How do you know the calibration error is linear?
It may be right on at 1.060…
My point to the OP is that the hydrometer is a good estimate for the amount of sugar in your wort/beer. Its not exact.
[quote=“roffenburger”][quote=“dmtaylo2”]I have a faulty hydrometer. It reads 0.003 too high, which needs to be subtracted every time I use it. And how do I know this? Measure the gravity of plain cool water. If this reads 1.003, it is obviously reading too high! But that doesn’t make the hydrometer worthless. It just needs the readings adjusted. This sort of test is essential for every homebrewer who is concerned about the accuracy of their hydrometer.
Also key with any hydrometer reading is the temperature. Try to always measure at about 60 F for the greatest accuracy. I agree that the commonly used temperature adjustment tables seem to be a little off. You need to measure with the temperature in the 60s (i.e., the ideal fermentation temperature for most ales) whenever possible.[/quote]
How do you know the calibration error is linear?
It may be right on at 1.060…[/quote]
That was my thought too. If you have an accurate scale, it’s pretty easy to make calibration solutions for any SG you want using table sugar and water. Just remember to weigh the sugar, then weigh the water/sugar solution (don’t add water by volume), and make sure the sugar is totally disolved and mixed well before testing with the hydrometer.
The first hydrometer I had was garbage. The paper scale inside would side easily if you bumped the hydrometer at all. ALWAYS check the calibration before using.
Back off, men. I am a scientist.
Really, I am. I am pretty sure the error will carry all up and down the scale. You can quote me on that.
And I sir, am an engineer. I do applied science, which is a lot messier than theoretical stuff. :?
If the error is due to the little paper slip having slipped out of position, then you are correct and the offset will be constant all the way up and down the scale. If on the other hand the error is due to a flaw in the manufacturing of the glass, and the density of the stem is not exactly what is should be as was calculated before that paper slip was printed, then the error may NOT be constant.
[quote=“dmtaylo2”]Back off, men. I am a scientist.
[/quote]
Me too. You should know better then. I hope you know we are just giving you crap.
Sorry you couldn’t see the tongue in my cheek, or the wink that I didn’t post. It was a lame attempt at being funny. Ever seen Ghostbusters?
I saw it. Missed the reference though… 
I’m a beer drinker. :cheers: What are we talking about?
Sometimes I have a difficult time decyphering whether the hydrometer says 1.017…1.016…1.018…damn thing is hard to tell sometimes. I’ve been wondering recently if residual co2 in the beer makes the OG higher than it really is.
[quote=“Beersk”]Sometimes I have a difficult time decyphering whether the hydrometer says 1.017…1.016…1.018…damn thing is hard to tell sometimes.[/quote]Get a low-range hydrometer that only covers 0.980 - 1.020 for accurately reading the FG.
