Just finished brewing my winter ale and the gravity turned out way lower than expected. My grain bill for the 10 gal batch was: 22 lbs 2-row 1 lb Crystal 40 L .5 lb de-bittered black Mash temp 152 F for 60 min. Not including spices and hops because I don't think this should affect gravity. Anyway, I usually get an OG in the 1.072 range but this time I got 1.034. Any ideas on what the #@#??!@ happened? Did the homebrew guy sell me the wrong grain? I fly sparged for about 45 min. I feel like I wasted a whole brew day. Should I dump it and try again or add some light malt extract? I don't want it to taste bad. This brew is always tasty and my friends always want some. Any advice is much appreciated.
It is possible you were way off on your temperature for your mash/sparge, although this would be impossible to check at this point (but you could test the thermometer for accuracy and/or sticking, if applicable). It could be a bad crush of the grain, which you might be able to discern by looking over the spent grains. Also, are the spent grains sweet to the taste? The sugar went somewhere, assuming the starches were converted.
Depending on the PPG of that base malt, you would need a mash efficiency somewhere around 85% or more to get an OG of 1.072. But clearly something is wrong if that 1.034 is accurate. Assuming the grain was crushed properly, I suppose it is possible you got the wrong grain, something with very low diastatic power. Did the base malt seem darker than usual?
I wouldn't dump it. I'd be inclined to just to see how it turns out. But if you want to add extract, just make sure you sanitize it first it first by boiling. I'd use the minimum amount of water needed to dissolve it.
Probably too late for this, but you could just have made half the expected volume. As Vikeman suggested it could be the base malt, the crush (their mill may have slipped a bit), the mash temperature, your hydrometer (is it correct & did you correct for temp?). 1.034 is way off, but it is always better to ride it out and decide one it is is fermented, as you have already invested the most time & money.
Check your thermometer(s). My efficiency dropped from 75-80 to barely 60% when my mashing temperatures were off.
