stuck fermentation with bubbling airlock?

So I recently brewed a IIPA, starting gravity 1.078, and pitched in WLP 051 - California V Ale. It went down to about 1.020, but I wanted it lower, so I pitched in a 2 L starter of WLP 001 and raised the temperature from 69 F to 71 F.

The airlock started bubbling about every 30 seconds or so, but after two days, it's still at 1.020. I'd like it to finish lower, but don't know if there's much I can do at this point. Any ideas?

thanks

Is it an extract beer? If so, my experiencewith an all extract beer has been a finishing gravity of around 1018-1020. If not, then what was your mash temp, is your thermo, and hydrometer calibrated, there are so many variables, what is your process, list that along with your recipe, and we can give you a better answer.

Hey, here's the info from the brewing session

21.3lb American 2row (81.9%)
3.1lb Munich 10L (11.8%)
1.3lb Carapils (5%)
0.3lb Crystal Malt 60L (1.3%)

Strike water 155F Mashed at 145F for 60 min
Added 2tbs of Mash5
Mash pH ~5.5-5.6
Raised to 155F for 30 min

it's a clone recipe for firestone union jack

thanks for the help!

oh, and the gravity reading was taken with a refractometer and a hydrometer

1.078 down to 1.020 is about 74% attenuation. That is right in the ballpark for the WLP051 with an average of 70-75%. Maybe try going with the 001 next time or even the WLP007. Both of these will finish more dry although the 007 tends to leave a little more sweet malt flavor. Also, make sure to calibrate your thermometers. I had a problem with a couple brews not finishing out and found out my thermometer was reading 4-5 degrees low.

If you want to try to get it lower, you could re-pitch a lager yeast. Lager yeasts tend to be able to chew through a little more sugar. I've never tried it myself, but I have heard from people that it can work.


Also, what temp did you ferment at? And did you pitch a starter of the 051?

i pitched a 5 liter starter of the 051, and then pitched a 2 liter starter of 001 once it was down to 1.020 and I was fermenting at 69 f, then raised the temp to 71. it's still reading at 1.020 gravity, but the airlock is still bubbling... i don't get what's going on

i used my thermometer on the blichmann kettle and also a digital therm during the mash, so i'm pretty sure it wasn't mash temp... :s