Gravity way off, what could've happened?

[b4k4]

This was my first all grain brew. Used one of those igloo cooler conversion mashtuns. Held the grains at between 140-150 for 75 minutes. Poured 168 degree water over the grain bed as it drained into the kettle. Brought to a boil for a hour, chilled, and transferred to bucket.

Recipe was for an imperial stout. 13lbs 2-row, 5.75 lbs other grains

Beersmith called for 6.4 gallons of water at mash in, 2.8 gal for sparging.

My gravity was supposed to be 1.104, but I'm reading 1.04. How could this have happened? Any suggestions for how to salvage it?

Should I just pitch and see how it goes? Can it sit overnight till I can pick up some DME to beef it up and then pitch?

 

[day_trippr]

Jeeze, the grist bill seems about right for 5 gallons to the fermentor to hit ~100 points OG.
So, ~30% efficiency. That's crazy low. Did someone forget to actually crush the grain?

You'll need to add around 7 pounds of DME to hit ~1.100 "OG".
You'd have to draw a few quarts of wort off to boil that up before cooling and adding it back in.
Maybe the better part of valor is to call this batch a small porter...

Cheers!

 

[b4k4]

Yeah I just pitched. Was gonna have a chocolate raspberry imperial stout, but a chocolate raspberry small porter could be interesting

Yeah 30% seems pretty terrible. I ran the grain through my LHBS's mill myself so they were definitely crushed.

 

[BlueHouseBrewhaus]

This was my first all grain brew. Used one of those igloo cooler conversion mashtuns. Held the grains at between 140-150 for 75 minutes.

So was it closer to 140 or 150? If the grains weren't mixed well and the temp was closer to 140, that could explain the poor conversion. Mash range is typically from 148-156. You can mash a little outside that range but not too far. Also the lower your mash temp, the longer it takes for conversion.

 

[b4k4]

After I added the water and stirred the mash I took a temp of 149 before closing up the mash tun. Was closer to 140 after 75 minutes

 

[jrcrilly]

It isn't easy to achieve only 30% efficiency these days. It is far more likely that the gravity sample was taken from wort that wasn't properly mixed, and the actual OG was much closer to what was expected.

 

[jbunton]

Did you do a temp correction on your hydrometer measurment?

 

[kh54s10]

I think there are probably several problems in tandem here. It would take around 22 pounds of grain to hit 1.104 OG. Yet, 1.040 would be really low for the grainbill, almost impossible to not be higher.

Did you end up with the proper volume? Calibrated hydrometer? Sample at the right temperature for the hydrometer?

If fermentation hasn't started take another gravity reading.

 

[b4k4]

I haven't calibrated my hydrometer so that could be an issue. The 1.04 was read at about 80°, maybe a little more

I did end up with about a gallon more than I was aiming for. My dang wort chiller sprung a leak at the hose clamp when I'd stepped away for 15 minutes