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View Full Version : What do you use to measure SG?



jaxn slim
01-12-2010, 05:10 PM
I've been using a hydrometer for about 3 years now. Since my experience is mostly in beer, it has been very practical. However, now that I'm getting into 1-gallon batches of mead which require several SG measurements, it does not seem as ideal to siphon out 1/4 cup for each gravity test.

Do you use refractometers? I know nearly nothing about these. Are there certain things to look for in them. Do you have a specific one to recommend?

Or am I thinking about this all wrong?

AToE
01-12-2010, 05:20 PM
I use a hydrometer and just sanitize everything well, and then dump the sample back into the main fementer.

I know I'm in the minority in that practice, but I haven't had a problem yet (I thought I had contaminated batches at one point, but it turned out to just be floating honey gunk, wax particles and such).

For 1 gal batches I agree with you, even a single sample or two can leave you with headspace issues and seems like a high % waste.

JamesP
01-12-2010, 06:22 PM
refer to http://www.gotmead.com/forum/showthread.php?t=7453&highlight=method+weight If you only want qualitative not quantitative information on the fermentation progress (in english, is it still fermenting or has it stopped),

then weigh your carboy (assuming small batches that your scales can measure).

When there is no change in weight due to CO2 escaping through the air lock, then fermentation should be near its end, so take your final gravity hydrometer readings only then.

If you do a combination of weight and hydrometer readings (trying to minimise loss of must volume), then you can start to predict SG by weight change, which may give you more quantitative information.

Fermentation progress is probably some inverse exponential decay, like:



SG
|
|x
| x
| x
| x
| x
| x
| x
| x
+---------------------------------------------------------------
time ->

skunkboy
01-12-2010, 07:40 PM
When I can be bothered to use something I use a simple hydrometer and tube.

JimSar
01-12-2010, 08:50 PM
I've also used AtoE's technique with no problems. However, I've recently done parallel readings using both a hydrometer and refractometer, using the following website to "adjust" the refractometer readings:

http://brew.stderr.net/refractometer.html

I find the results generally within .001 to .002 of each other, which I consider to be close enough. So, for gallon batches, I've just been using my refractometer exclusively. I use a sanitized syringe to pull a small sample, use two drops for the refractometer, and the rest is for tasting.

Kee
01-12-2010, 11:02 PM
I probably shouldn't admit this, but I don't use one as much as I probably should with a 1 gallon. I'll take the SG, and I assume I hit the 1/3 sugar break about day 3-4. If I'm good, I'll check. I keep an eye on it to ensure it's progressing nicely (and keep it under airlock). I'll check the gravity again in a few months. It usually finishes fine. I'm much, much better about my larger batches.

There's another thread somewhere that has hydrometer balls. You drop the balls into your mead and, depending on the gravity, the balls drop. They were a little expensive. I think there was another thread about a leave-in style hydromenter but I don't know if the mouth of a 1-g is wide enough for it. I haven't tried either.

wayneb
01-12-2010, 11:13 PM
For small batches (gallon sized or smaller), I'd definitely recommend a refractometer. Just look for one that is calibated in increments useful for winemaking (generally 32 to 0 brix), and you'll do fine. I admit to being somewhat old school and I still use my hydrometers for most of my measurements, both because I don't have to calibrate the readings for fermentation in progress (as you do with a refractometer), and I like to have that sample tube available for organoleptic sensory analysis (aka tasting) after I get done with the reading! ;D But I almost never make batches as small as a gallon any more, so the loss of samples to testing generally isn't an issue for me.

TheTooth
01-13-2010, 12:53 PM
I got a refractometer for my beer making. It works awesome for everything else as well. I haven't touched the hydrometer in well over a year now.

Medsen Fey
01-13-2010, 01:06 PM
I got a refractometer for my beer making. It works awesome for everything else as well. I haven't touched the hydrometer in well over a year now.

I take it you don't do a lot of backsweetening (or at least measurements after backsweetening) or blending. For those task a refractometer just isn't too practical. Don't get me wrong, I'd rather lose a limb than my refractometer, but every tool has its use including the hydrometer.

jaxn, you can also use a fresh egg like our forefathers did.

Kee, here's the thread on Brew Balls (http://www.gotmead.com/forum/showthread.php?t=14948&highlight=brew+balls).

Metal Fireworks
01-13-2010, 06:10 PM
When you are talking about the "tube", is that the tube the hydrometer was sold in? It seems narrow and the hydrometer would give inaccurate readings due to contact with the sides. I have yet to try it but was just wondering if this was one I should use.

skunkboy
01-13-2010, 06:44 PM
I don't use the same tube that the hydrometer came in, I have something more like the following to put the fluid and hydrometer in :

http://www.opticsplanet.net/nalge-nunc-pmp-hydrometer-jar-nalgene-6230-0500.html

wayneb
01-13-2010, 06:56 PM
I have a glass graduated cylinder that I'll use most of the time (I'm old school, remember?), but if I'm in a hurry I'll use the tube that the hydrometer came in. Although narrow, it does have enough clearance to allow an accurate reading to be had if you're careful to keep it level and are good at spinning the hydrometer as you drop it into the sample.

Medsen Fey
01-13-2010, 07:04 PM
I have a glass graduated cylinder that I'll use most of the time (I'm old school, remember?)

Yeah Wayne, when exactly did you stop using the fresh eggs? :laughing11::laughing3:

wayneb
01-13-2010, 07:19 PM
Yeah Wayne, when exactly did you stop using the fresh eggs? :laughing11::laughing3:

When I dropped one on the floor! ;D

Seriously, I did do a batch using a floating egg to measure initial gravity once, back in the 80's, during one of those experiments of mine when I was trying to be "historically accurate."

jaxn slim
01-14-2010, 11:09 AM
When you are talking about the "tube", is that the tube the hydrometer was sold in? It seems narrow and the hydrometer would give inaccurate readings due to contact with the sides. I have yet to try it but was just wondering if this was one I should use.

If you spin the hydrometer around in the tube before taking your reading, it's not usually a problem.

tatgeer
01-16-2010, 11:43 PM
There's another thread somewhere that has hydrometer balls. You drop the balls into your mead and, depending on the gravity, the balls drop. They were a little expensive.

My husband got me some of these for my birthday a couple of months ago - I have them in a 5-gallon batch right now, and they're pretty useful. They're not calibrated in such a way as to replace a hydrometer completely, but they do give a good handle on how fermentation is progressing. I tried them in some beer, but the krausen was too thick to really see the balls!

http://www.brewballstore.com/