some process, very low OG?

i've been doing all grain for about 2 years and i've probably done ~12 batches. my efficiency has always been between 75-80%. the last two batches, however, my OG was 15-20 points low. yesterday i brewed a belgian quad with 16lb of grain. mashed at 149F with 21 quarts of water. i split the sparge, like i always do, with 2 rounds of ~2.75 gallons @ 166F. this is the same process i've always used. the quad should have been 1.095, but, according to my hydrometer and refractometer, my OG is 1.073. i'm very pissed. any ideas on what would make me start dropping 15-20 points all of the sudden?

There are four likely candidates:

1.) Changes in the grain crush. If the grain was crushed too finely or too coarsely, efficiency will suffer.

2.) Dough balls. These take a big toll on efficiency.

3.) Thermometer out of calibration - meaning that you didn't mash at the temperature that you thought you mashed at, meaning you may have gotten incomplete conversion.

4.) Channeling - if your grain bed didn't set properly during lautering and sparging (mostly a problem if you fly sparge or don't stir up the grain bed between batch sparges), you may have formed channels in the grain bed, meaning that the sugars don't get rinsed from most of the grains.

Hmmmm, do you crush your own? Maybe something happened to the mill gap? has anything changed that you can recall? Equipment or process?

of those possibilities, it had to have been the crush. i don't have a mill and i get all my grain pre-milled from austin homebrew. i know it wasn't the temp because i use 2 separate thermos, both of which have been calibrated and read the same. i also stir thoroughly and know there were no dough balls or channeling issues. i've still got the spent grain pile in the back yard if a picture might help confirm the crush.

has anyone else been having problems with pre-milled grains from ahs?
should i add some more dark candi sugar or regular table sugar to get the OG a little closer to the target?

One other possibility is the high OG of the brew. In my case, if I am brewing a beer with an OG < 1.060, I have no problems reaching my normal efficiency. If I am brewing a beer with a gravity > 1.060 and < 1.075 (approx) I have to slow down the sparge (I fly sparge), or I start losing efficiency. If I want a gravity > 1.075, then I am going to lose efficiency unless I do a parti-gyle or add fermentables post mash.

-a.

anyone think i should add more sugar into the fermenter to raise the OG, or should i just leave it alone?

lpdb185 said:

of those possibilities, it had to have been the crush. i don't have a mill and i get all my grain pre-milled from austin homebrew. i know it wasn't the temp because i use 2 separate thermos, both of which have been calibrated and read the same. i also stir thoroughly and know there were no dough balls or channeling issues. i've still got the spent grain pile in the back yard if a picture might help confirm the crush.

has anyone else been having problems with pre-milled grains from ahs?
should i add some more dark candi sugar or regular table sugar to get the OG a little closer to the target?

Click to expand...

well, i just posted a similar thread today because my OG was way lower than anticipated. guess were i got my grains? yup...ahs. id hate to name drop or put the blame on them, but this has happened a few times with them now. my process has been the same for years with the same equip. i usually hit my numbers fine. i like ahs for a number of reasons over many other online hbs. i hope they can resolve this issue...