How to check SG of running from Mash Tun

dregus · 09-10-2010, 02:33 AM

Hello all,

I have brewed about 12 batches on my homemade home brew system. Everything I have read says that you should but the runnings off when you reach the pre-boil volume or when the OG of the runnings reaches about 1.020. How do you all measure this when the runnings are at 170ish degrees?

I am also wondering so I can figure out the efficiency of my system.

Dennis Regus

Blender · 09-10-2010, 02:43 AM

Best and quickest way would be to use a refractometer. Morebeer Vid

mattd2 · 09-10-2010, 02:46 AM

Quote:

Originally Posted by dregus

Hello all,

I have brewed about 12 batches on my homemade home brew system. Everything I have read says that you should but the runnings off when you reach the pre-boil volume or when the OG of the runnings reaches about 1.020. How do you all measure this when the runnings are at 170ish degrees?

I am also wondering so I can figure out the efficiency of my system.

Dennis Regus

Are you fly sparging? Also I thought it was 1.010?
The only quick way to do it would be to buy a refractometer (sp?), which only takes a small drop of wort for the test so it cools to ambient quicker (and some have a temp compenstation in them aswell).
Other than that I don't think many worry about the 1.010.

Or you could just take a OG reading at the end of you sparge and wait for the whole thing to cool just as a check how close to 1.010 you are getting.

shortyjacobs · 09-10-2010, 01:50 PM

Quote:

Originally Posted by mattd2

Are you fly sparging? Also I thought it was 1.010?
The only quick way to do it would be to buy a refractometer (sp?), which only takes a small drop of wort for the test so it cools to ambient quicker (and some have a temp compenstation in them aswell).
Other than that I don't think many worry about the 1.010.

Or you could just take a OG reading at the end of you sparge and wait for the whole thing to cool just as a check how close to 1.010 you are getting.

I have also heard 1.010 for fly sparging. For batch...don't worry about SG, just do your batch sparges and don't worry. The refractometer is the quickest and easiest method, however I wanted to correct one tiny point in your post. The Automatic Temperature Correction (ATC) refractometers correct for AMBIENT temperature, (as in, it doesn't matter if it's 40°F or 90°F outside when you use it), not for WORT temperature. This is no big deal though, as the thermal bulk of the refractometer is so much higher than that of a single drop of wort, and the wort cools to refractometer temps essentially instantly.

**Bobby_M** · 09-10-2010, 02:10 PM

Well, documenting the runnings gravity (and volume) is meant as a troubleshooting tool, not something you'll always do. If you just want to check efficiency, measure the total preboil volume that went into the kettle, stir well, then take a sample. You can collect it right in your test tube, put it in the freezer for 5 minutes and then test it.

janitorjerm · 09-10-2010, 02:25 PM

Could you use something similar to a "parrot"? Like the ones distillers use.

**winvarin** · 09-11-2010, 03:41 AM

Or you could go the poor man's route. Pull a sample and drop your hydrometer in, then adjust for temperature. There are sites out there that will let you just put your gravity and the temperature, and make the adjustment for you.

I use Dave's Dreaded SG calculator http://dd26943.com/davesdreaded/tools/convert.htm
from time to time

**samc** · 09-11-2010, 04:58 AM

+1 as Bobby_M said.

I've checked mine with Refractometer but don't bother with it very much. Once you know your system it seems pointless unless you suspect issues due to a stuck sparge or other equipment issues.

brewingkitty · 09-11-2010, 05:28 AM

i use my refractometer and it's a snap..

pkeeler · 09-11-2010, 05:35 PM

Yes, you can certainly go lower than 1.020; 1.010 is more like it.

I usually let it sit for a bit and adjust for temp. But I don't see why you couldn't keep some very cold water around. Measure your hydrometer cylinder, lets say that is 1 cup. In a measuring cup, put in 1/2 cup of hot wort and 1/2 cup of cold water. If the wort is 150, and the water is 40, then the hydrometer would be reading at 90-95 (probably 90 with the stirring you should do). That isn't 60 deg., but the adjustment and margin for error is much lower than at 150-170.

Don't forget to double the reading after making the adjustment.

Even if you are not worried about dreg runnings, it is a good idea to take the SG of your final runnings. If you find, for instance, that they are 1.025, you know you are leaving a lot of sugar in the grain bed and killing your efficiency (which raises your cost).