Originally Posted by mr_tripp
I have been brewing for about 3 years (2 years all grain) and have had several good beers and a lot more bad ones. I recently built an all electric system for indoor brewing. I have 2 aluminum pots with 2000w electric water heater elements and I use Ranco digital thermostats to control the elements. My last 4 batches have resulted in a stuck fermentation of about 1.025. Here is my process:
One of my pots has a screen at the bottom and I set that one to 166F and add a little gypsum salt according to my city water (1 tsp. per gal.) then add my crushed grains (I use a corona mill and get a fine grind, but there is still some husks). The temp ends up at 152F. I turn off the element before I mash in and don't turn it on during the mash.
At the same time I set the other pot up to 152F and place my immersion chiller in it and pump the wort out of the Mash tun through the copper pipe and measure the temp of the wort coming out to make sure it is at 152F and set the Hot Liquor tank thermostat to the temp of 152F of the wort coming out of the immersion chiller.
Here is where I have a little problem. The temp probe coming out of the immersion chiller is 152F but the other temp probe at the bottom never reaches 152F it is always around 147F even if I stir.
After 60 minutes I raise the temp in the Liquor tank to 170 and fly sparge. I usually get about 80-84% efficiency depending on how I sparge (my last batch drained to fast on the mash tun).
I then add the wort back to the empty hot liquor tank and it becomes my boil kettle. I boil for 60 minutes and hit my final gravity. I made a 2L starter (W1056) about 24 hours in advance but my wort did not chill all the way to 67F so I put it in the bucket in the chamber and pitched in the morning. I get 24-36 hours of good fermentation, then it stops at 1.025. I did not use oxygen but I do splash it pretty good when it comes out of the pump and I shake it. I also shake and stir the bucket during fermentation.
I am using a refractometer (ebay) and I would be ok if the beers tasted ok, but they taste overly sweet. I made a starter and I used DME following Jamil's recommendation and the gravity read 1.040, so I don't think the refractometer is off.
The only thing I can think of is the mash is higher than it is reading on my ranco thermometers and I am getting unfermentable sugars. When I add them to the boil they only read 209F so I guess they could be a little off, but they both read 209F so I know one is not off. From my understanding there is no way to calibrate these.
I also used Jamil's American Pale Ale recipe adjusted to 84% efficiency. The last 4 batches were Jamil's. I did 2 Blondes and 2 Pale ales and all stopped at 1.025.
Any suggestions or questions would be great. Thank you!
Just a guess:
Are your thermometers properly calibrated? It hasn't been a problem before these batches, but did you get some new equipment? Maybe you are mashing at a higher temp than you are aware. That may also be why your two thermometers are reading different temps.
Maybe I'm completely off. 1.025 is pretty sky-high for something like that, but it wouldn't hurt to grab another thermometer and give 'er a go