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I brewed a Dogfish Punkn clone that was rather heavy on the sediment. I pitched a pretty healthy yeast starter that was working for 30 hours before being pitched probably around 80 degrees, perhaps slightly more than the room temp. The yeast didn't take off, airlock activity was brief and underwhelming. It began at the 48 hour mark and lasted until the 60 hour mark. The krausen rimming the carboy is short, perhaps less than an inch. Should I pitch a new batch of yeast? It has been fermenting for one full week. I wasn't able to take a gravity reading because I busted my hydrometer. Any thoughts would be greatly appreciated.

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    If you weren't able to get an OG do you know what the recipe said the OG should be? have you tasted it? you really need gravity readings to be able to tell if its done... – GerryEgan Sep 2 '14 at 17:38
  • Along with Gerry's question about (expected) OG, how many liters was your starter and how much yeast did you pitch into it? – Scott Sep 2 '14 at 18:11
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You're going to have to take a gravity reading in order to determine whether or not fermentation has completed. It clearly did ferment given your description of events, but now it becomes a question of how much, and whether or not it has completed.

I suspect you may have under-pitched despite using a yeast starter, which would cause an extended fermentation past what normal ale fermentations take. Under the right circumstances, most ale fermentations develop a krausen well before 24 hours and should complete in about a week, assuming normal fermentation temperatures, average gravity, proper yeast pitch rates, and average yeast attenuation. Altering any of the above variables can dramatically alter the time needed to ferment to completion with varied consequences, either good or bad. For example, I recently brewed a Belgian Tripel using a new Belgian yeast strain boasting an unbelievably high 85% - 100% apparent attenuation. In the second week of fermenting, it dropped a further 5 gravity points. A lesser attenuating ale strain would have completed fermentation in a substantially shorter period.

Unfortunately, pitching more yeast may have likely been the solution back in the beginning a week ago, but will not benefit you at this point in the fermentation, unless you have a stuck fermentation, in which case you'll want to follow steps to correct the stuck fermentation. Any consequences of under-pitching yeast will have already developed by now. Best to wait it out, take gravity readings to see if it has completed, correct if stuck, and eventually go to bottle/keg.

For future reference, use Mr. Malty's yeast pitching rate calculator to determine the correct size for your yeast starters, it should hopefully prevent this in your upcoming batches.

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  • What is the best way to get a gravity reading without contaminating the beer? Just dropping the sanitized hydrometer straight into the carboy? Are there any risks associated with repitching and if so, are they substantial or negligible? – g0dluvsugly Sep 3 '14 at 0:25
  • You're correct. Sanitize the hydrometer (I use a spray bottle of Star San or dunk it for 30 seconds in a bucket filled with it). There aren't any negative consequences to re-pitching yeast at this point (other than potentially wasting money/yeast). The bulk of consequences associated with under-pitching develop within the first 3-5 days of fermentation. Pitching more yeast at this point without a gravity reading is likely a waste of yeast. I would not recommend it. At this point your best bet is to ride it out and take hydrometer readings to determine if it has completed. – Scott Sep 3 '14 at 14:22
  • My homebrew shop finally opened yesterday after taking an extended holiday, so I managed to get a new hydrometer. The reading was close to 1.020. If the recipe is correct in its assessment, then the OG would've been somewhere near 1.070. Looks like fermentation occurred without really even showing it. Strange since the batch before wound up nearly all over the ceiling of my closet and stunk the house up of bread and C02 for a week. Just goes to show that patience is a virtue, and that you have to trust the process. I took a sip and it tasted every bit of boozy, too. – g0dluvsugly Sep 4 '14 at 16:33
  • What was your anticipated FG? It may be that it is still silently fermenting. You'll probably want to wait a week and then take daily gravity readings. Once it goes for three days without changing gravity, it's safe to go to bottling. – Scott Sep 4 '14 at 16:44

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