F.G. 10 points low, WTF?

I have had the same problem on my last two batches of beer and I need some help and advice. As the title says, both of my last two batches have finished 10 points lower than calculated ( 1.003 rather than the 1.012 or 1.014 that they should have been). After the first batch, I figured it was due to infection, so I bought a new primary bucket and bleach bombed everything else that contacts the beer post boil. Next batch, I had the same problem. For both batches, the beer tasted off (not sure how to describe the taste, sour maybe?) and had a watery mouth feel. From what I have read, this all seems to point to infection and it may well be, but is there anything else that can cause a beer to ferment down so far?

BTW, both batches have used US-05, if that is significant.

High attenuation can be the result of a large number of factors. Are you doing all grain? If so, it could be your mash temps being low.

It could be an infection, but if it doesn't taste or smell funky, I would be doubtful of that.

Is your hydrometer calibrated? Does it read 0.000 in water?

assuming your hydrometer is calibrated as mentioned, if you post one of the recipes, the OG, and a run down of your process it would probably help us troubleshoot.

I have checked my hydrometers, both read 1.000 in distilled water. I have also calibrated my thermometer, so I think I can rule out measurement error. I am brewing with LME and am doing full wort boils. I chill with an immersion chiller and pitch rehydrated US-05 when cool and in primary. My last recipe is as follows:

6.6 lbs light LME
1/2 lb crystal 80
1/2 lb crystal 10
.5 oz hop additions at 60, 15, 0 min
1 tsp irish moss at 15 min
Us-05 (rehydrated) pitched when cool.

Grains are steeped in 1/2 gal water at 155deg for 30 min, rinsed with another 1/2gal, the rest of the water for the boil is R/O water from my LHBS.
According to the calculator at Brewer's Friend, My OG should have been 1.051 (it was) and the FG should have been 1.014 ( I got 1.004).

I would lean towards the extract being the culprit. You can get differing amounts of fermentables from batch to batch, and thus end up with under or over attenuated beers.

As far as the off-flavor...

Describe as best you can. Is it prevalent, or there in the background? The watery could be due to the lower FG. Are you getting a boozy/alcoholic flavor in there too?

You could add a non-fermentable sugar to get your body and mouthfeel back. Make a syrup with lactose and add to taste.

The off flavour is in the background,I can't really describe it, i want to say sour, but that isn't quite it. The mouthfeel is a bit thin, but there are no overly boozy flavours there.

philjohnwilliams said:

The off flavour is in the background,I can't really describe it, i want to say sour, but that isn't quite it. The mouthfeel is a bit thin, but there are no overly boozy flavours there.

Click to expand...

Hmmm...

Well, replace all your hosing since it's cheap. If you can see any scratches in any plastic equipment, replace that too. Anything that's dishwasher safe, assuming you have a dishwasher, run through there with no soap or rinse agent.

Also, be careful with bleach as your sanitizer. Rinsing well is key as you can get off flavors from it. I've never used it or tasted said off flavor, so I can't describe it off hand for you.

I can only think of 2 possibilities: 1) the extract is way too fermentable, and 2) there are nasties getting into the wort and causing non-fermentables to be fermented.

So, since you bleach bombed everything, I think I'd target #1 first so you don't have to buy new stuff. I guess first off, did you use the same LME in both batches (same batch of LME from the same LHBS?). I suggest if you buy your next extract from your LHBS, try the amber LME, or try DME, but do not use the light LME from the same LHBS. Maybe order some online if you really want to rule that out.

I assume you don't use bleach as your typical sanitizer, but if you do, please do yourself a favor and switch to StarSan.