troubleshooting under-attentuation

[sowoah]

Hi guys. Started brewing 4 months ago. 7 all-grain batches on an E-herms system. They have all turned out pretty well, my only problem is consistent under-attenuation. I'm hoping you guys can help me identify what I should try. More about my set up:

I have mashed all of the beers between 149-150. I get around 75-80% efficiency on the mash. I aerate with a wine degasser on a power drill for ~30 seconds after splashing wort through a straining funnel into fermentor.

I have a brew pi set up on a chest freezer, regulating temps within 0.1. Tap water is pretty warm so I usually pitch at 80 and bring it down to fermenting temps within a few hours. I tend to ferment on the cooler side and ramp up after a couple of days. I leave them in primary for at least 10 days, often longer. I make sure gravity has not changed in a few days before crashing/bottling.

I have reused yeast a lot, and even harvested from bottle dregs to great success. I have a 2L flask and a stir plate, so I feel like my starters are pretty healthy. I cold crash them and see that I have a nice amount of slurry going into those batches.


Below are the batches, beer style, yeast used, temps, and gravity/attentuation.

As you can see, the first couple of batches were good, then it all went downhill. Is reusing yeast my problem? Am I possible making wort that is somehow less fermentable? Do I need pure O2 or to aerate longer? Am I stunting the yeast with temps? I know it may be hard to pinpoint from this info, but just looking for what I should try first.


Batch 1: Pale Ale. Fresh US-05 packet, rehydrated. 64 for 2 days, slow ramp to 68 over 2 weeks. OG 1.053 FG 1.012 77%.

Batch 2: Wit. 1L starter from Hoegaarden dregs. 68 for a day, free rise to 76 over a week. OG 1.042 FG 1.008 81.2%

Batch 3: ESB. Fresh S-04 packet, rehydrated. 61 for a couple of days, rise to 66 over a few days, low 70s for a few more days. OG 1.060 FG 1.018 70%.

Batch 4: RIS. some slurry straight from Batch 3(S-04) plus 1.5L starter from batch 1(US-05) slurry. 64 for 2 days 70 for a day, then 76 for a week as fermentation had already seemed to stop. OG 1.09 FG 1.03. Very vigorous fermentation, hit FG at day 4. Transferred to secondary after 2 weeks Same gravity after 2 months in secondary.

Batch 5: Partigyle from batch 4. didn't log but it did so-so with a fresh packet (full packet US-05 into a 3G batch, still slight underattenuation)

Batch 6: IPA. New 1.5L Starter from previous starter from batch 4 (US-05). 64 for a couple of days then low 70s for 2 weeks. OG 1.075 FG 1.025. 66.7%. This really ruined the beer. It's too sweet.

Batch 7: Lager. 2 packets of W-34/70, sprinkled on at 65 degrees. Ferment at 53 for 5 days, free rise to 68 by day 9. Crash to 35 for 2 weeks. OG 1.052 FG 1.015.

 

[TheMadKing]

Hi guys. Started brewing 4 months ago. 7 all-grain batches on an E-herms system. They have all turned out pretty well, my only problem is consistent under-attenuation. I'm hoping you guys can help me identify what I should try. More about my set up:

I have mashed all of the beers between 149-150. I get around 75-80% efficiency on the mash. I aerate with a wine degasser on a power drill for ~30 seconds after splashing wort through a straining funnel into fermentor.

I have a brew pi set up on a chest freezer, regulating temps within 0.1. Tap water is pretty warm so I usually pitch at 80 and bring it down to fermenting temps within a few hours. I tend to ferment on the cooler side and ramp up after a couple of days. I leave them in primary for at least 10 days, often longer. I make sure gravity has not changed in a few days before crashing/bottling.

I have reused yeast a lot, and even harvested from bottle dregs to great success. I have a 2L flask and a stir plate, so I feel like my starters are pretty healthy. I cold crash them and see that I have a nice amount of slurry going into those batches.


Below are the batches, beer style, yeast used, temps, and gravity/attentuation.

As you can see, the first couple of batches were good, then it all went downhill. Is reusing yeast my problem? Am I possible making wort that is somehow less fermentable? Do I need pure O2 or to aerate longer? Am I stunting the yeast with temps? I know it may be hard to pinpoint from this info, but just looking for what I should try first.


Batch 1: Pale Ale. Fresh US-05 packet, rehydrated. 64 for 2 days, slow ramp to 68 over 2 weeks. OG 1.053 FG 1.012 77%.

Batch 2: Wit. 1L starter from Hoegaarden dregs. 68 for a day, free rise to 76 over a week. OG 1.042 FG 1.008 81.2%

Batch 3: ESB. Fresh S-04 packet, rehydrated. 61 for a couple of days, rise to 66 over a few days, low 70s for a few more days. OG 1.060 FG 1.018 70%.

Batch 4: RIS. some slurry straight from Batch 3(S-04) plus 1.5L starter from batch 1(US-05) slurry. 64 for 2 days 70 for a day, then 76 for a week as fermentation had already seemed to stop. OG 1.09 FG 1.03. Very vigorous fermentation, hit FG at day 4. Transferred to secondary after 2 weeks Same gravity after 2 months in secondary.

Batch 5: Partigyle from batch 4. didn't log but it did so-so with a fresh packet (full packet US-05 into a 3G batch, still slight underattenuation)

Batch 6: IPA. New 1.5L Starter from previous starter from batch 4 (US-05). 64 for a couple of days then low 70s for 2 weeks. OG 1.075 FG 1.025. 66.7%. This really ruined the beer. It's too sweet.

Batch 7: Lager. 2 packets of W-34/70, sprinkled on at 65 degrees. Ferment at 53 for 5 days, free rise to 68 by day 9. Crash to 35 for 2 weeks. OG 1.052 FG 1.015.

Your temps looks ok honestly, have you double checked your actual beer temps to make sure your controller is working properly? If you set it at 61, and the beer is sitting at 55 then that would make a pretty big difference.

Also what do your grain bills look like? Are you using a higher than normal percentage of specialty grains?

What temp are your starters when you're pitching them? they should be the same temp if not cooler than your wort at fermentation temp. It might also be a problem if you're pitching warm (70) and cooling to mid (60's) right away (though this shouldn't be an issue).

 

[kombat]

Reusing yeast can impact their attenuation, particularly if they go from a dry beer to a sweeter, more malty beer. They get used to chowing down on the simple sugars, and become less inclined to consume the more complex sugars. Your mash temperature and procedure seems fine, the only other suspect in my opinion would be the recipes. Where are you getting the recipes from, and what percentage of unfermentables do they include?

 

[TheBrewingChemist]

If you cannot cool past 80 with your tap water, you may want to put a pre-chiller coil in ice water prior to your wort chiller. Alternatively you could wait to pitch your yeast until the wort gets down to fermentation temperatures. I generally never like to lower the fermentation temperature while in a growth phase. Depending on how fast the temp drops you could be putting part of the yeast population into a dormant state.

 

[porterpounder]

The only way to be sure of an issue with your process is to change one thing at a time. Slow, but educational process. Start with making sure your mash thermometer is calibrated and you're not mashing too high by accident. Start with fresh vs. repitched yeast, then maybe O2 vs. air. Then take a look at your fermentation process. 9 days for a lager even with the free rise may have been too quick before the crash. Also 2 weeks with an RIS then transferring may also have been premature. Once you transfer to a secondary then it is very unlikely your fermentation will have a chance to get going. I'm with the "avoid secondaries" school, but if you do them then make sure you're at terminal gravity before you transfer. It's a lot easier to fix fermentation issues in a primary (inc heat, rousing yeast, etc.) than after a transfer.

 

[sowoah]

Thanks for the replies so far. All of the recipes are my own, but the grain bills very closely follow popular recipes from here (averaging the top few recipes, usually) So far, other than the Wit (50% wheat) and the RIS (10% wheat/oat) my grain bills have been 100% barley malt with no more than 10% specialty grains. In fact I've dropped this closer to 0-5% lately for more ferment-able wort, with no success. I have done the last 2 beers (batch 6 and 7) with 95-100% Pacific NW Vienna malt, does anyone know this malt to be somehow lower attenuating than other base malts? Batch 3 and 4 were mostly Marris Otter. My best luck was 1 and 2 (USA 2 row)

I will test my temperature probes to make sure they are calibrated.

I use a immersion chiller to cool the wort, and once it gets down to about 90-100 I have to run the water through my herms coil with ice water in the HLT, but the tap water is so warm that it takes forever to get things down to 70, but 80 is much easier. Maybe I will just start pitching after a few hours once the freezer has brought the wort down.