Irish Red not Finishing

[kegnation]

I recently brewed an Irish Red 10gal all grain batch. Hit my mash temp @152 and OG @1.056. I pitched each carboy with one packet of US-04 sprinkled directly in. I went to bottle it after 8 weeks in primary(no secondary) and my reading was 1.029. I really liked the taste so I went ahead and bottled but I've had this problem with the last three batches (a stout, a witbeir, and now the Irish) I ferment in my basement which stays a pretty constant 64-66F. Should I ferment warmer or just pitch more yeast? here's my grain bill-Thanks for the help!!

 

[ArcaneXor]

The most likely culprit is a faulty thermometer, resulting in suboptimal mashing temperatures and partial conversion. Check your thermo. Check your hydrometer as well. If that's not the problem, re-evaluate your process (especially yeast preparation and wort oxygenation) and brew a beer specifically with the goal of reaching maximum attenuation - something like an all-Pils session Saison mashed at 148 degrees.

 

[jbaysurfer]

Agreed with above, but I'd also caution you that if you let your beer sit on the yeast for a good while, it will actually contained some dissolved C02 throwing off your hydrometer reading. Not so much as to add 10-20 gravity points to the reading mind you...but it could add 4-6 points.

So recalibrate your thermometers and thoroughly de-gas your hydrometer samples. My big beers that age the longest usually read 4 gravity points higher before I de-gas them. You can de-gas it by letting it sit out overnight, or taking a whisk to it, or any method of agitation/gas release.

 

[kegnation]

Thanks for the suggestions I've recently been keeping better records of my brews and really enjoy it! I will double check my thermometer I use when Im mashing in. What temp range would have this effect? Im guessing too high? I have a refractometer and put some starsan on it and it shot a zero. Is there another way to calibrate it?

 

[PlinyTheMiddleAged]

Are you checking fg with your refractometer? If so, there's your problem. The refractive index of alcohol is different than that of water. So, in the presence if alcohol, your refractometer will not read correctly. There are correction algorithms out there that try to compensate for the error. Using your supplied sg and fg, I estimated that your true fg is about 1.014 with an ABV of 5.1%.

I used this:
http://seanterrill.com/2012/01/06/refractometer-calculator/

 

[kegnation]

I had no idea that you couldn't check FG with a refractometer! Thanks a lot! I didn't think my beers were overly sweet but I went with the reading. Great info!!!

 

[jbaysurfer]

Good advice from Pliny. That reading isn't accurate. The algorithms approximate FG when you use the calculator and a refractometer, which is why I use a refractometer for brewday, mash, and OG, but a hydrometer for FG. But, as I mentioned, the hydrometer has a couple of it's own issues to look out for.

 

[jbaysurfer]

Oh btw, calibrate your refractometer with room temp distilled water, not starsan.