yeah i dont know what the deal was in this case. wlp090 on this recipe always rips thru it all very quickly. not unuasal to be done after 5 days. this one went almost 2 weeks before i got to taking a reading and kegging. i did decide to colect 1/4 cup of slurry and have got a yeast starter going just to see how that works this weekend when i fire up another round of this recipe.
Bummer man, I can’t see a reason why your FG would be higher. Sounds like you know what you are doing.
If ones does not allow for new cell growth on a pitch, one can end up with a poorly performing culture due to average yeast cell age and budding scars. At most, one needs 150 to 200 milliliters of thick slurry to fully attenuate 5 gallons of 1.060 wort, which usually requires one to crop around 250 to 350ml of thin slurry from a primary fermentation.
Wyeast states that thick slurry is usually composed of 40-60% yeast cells. One milliliter of thick slurry that is composed of 40% yeast contains 1.2 billions cells; hence, 150 to 200 milliliters of thick slurry contains 180 to 240 billion cells (viable cell count requires a microscope, a hemocytometer, and methylene blue). Wyeast even gives a way to estimate cell count by slurry weight. Slurry that contains 40% yeast cells weighs 1.1 grams per milliliter; hence, 150mls of 40% slurry should weigh approximately 165 grams.
The maximum cell density for 5-gallons (~19L) is 19 x 200 billion = 3.8 trillion cells. If we are starting with 200 billion cells, then we are looking at log2(19) = log(19) / log(2) = 4.3 (5 for good measure) replication periods after the lag phase has been exited until the culture has reached maximum cell density, which means that maximum cell density should be hit at 90 x 5 / 60 = 7.5 hours after the lag phase has been exited. With most ale yeast strains, that figure equates to about 12 +/- 3 hours between pitching and signs of active fermentation.
Hold on to your seat, I’m gonna agree with you! ;) years ago, after i had started re;pitching on a previous slurry, I wondered if I really needed all that yeast. I started dividing the slurry into thirds or halves and only pitching a portion of it. It was immediately clear to me that the beer I made that way tasted better than when I used the entire slurry for another 5 gal. 1.050-1.070 batch. No quantification, no blind tasting…it was obvious that cell growth produced a better beer.
I originally stumbled onto this information while listening to Garrett Oliver speak back in the nineties. He said that he periodically underpitched in order maximize new cell growth. I started to research the subject after hearing Garrett speak. Like humans, yeast cells lose fertility and undergo metabolic changes as they age.
Cue “Taxi Driver”…“you talkin’ to ME?” 
Must be the reason for a poor FG. I decided to use 1/3 cup slurry in yeast starter, and then pitched that into another batch. Already at 1.012 after 4 days and that’s right on the money for this beer and wlp090. Again, lesson learned and better brewer for it!
I went to the Mr Malty yeast calculator and just did a repitch of US-05 using about 85ml of yeast measured in a beaker. The 5 gallon batch took off fine (1 week from harvest from primary) at a 1.050 simple pale ale. I can’t say what the taste profile will be, but it is a significantly smaller repitch than I used previously…
When I got into repitching I was using the suggested ml of slury, but it was usually about the consistency of thick yogurt, way more cells than that runny stuff that comes out of a smack pack. Im certain I was way over pitching. My new way will be to save a quart of swirled yeast cake, then do a starter with ~90 mls of runny stuff.
Yeah, for simple ales that is what I am finding to be the best route!
Well the more I thought about it the more it makes sense. It only adds one step to the process and gives you a bunch of fresh new babies to make beer rather than a cup of old guys.
Yeah, that is my thinking. I am not saying I have science to back it up, but like Denny says try it and see what works for you. I find the lagers require a bit more than the ales, but the lagers are starting to support a bit less repitch thanI was doing. Taste and less esters and phenols are what I am seeing.
Zactly
and probably why this batch tastes not up to par. poor hop taste and smell ,and horrible off taste from stressed out yeast. down the drain with this one!
and the good news is, the batch i made last weekend by using 1/3 cup of the slurry and building a yeast starter came out perfect. its finished at 1.010 and hops and malt shinning bright!
Good deal!