I'm just returning to brewing after a couple years off from getting married, buying a house, moving, etc and am running into an issue with attenuation. With both an ESB and IPA all-grain brew that went nominally well, I can't get past 67% attenuation with yeast that should take me to 73-77% (wyeast 1335). In the hunt to figure out what idiot mistake I'm making, I went looking for brewing practice tests or homework items. Sadly, I'm not finding anything in print or on the web.

I'm looking for tests that might help me fine tune my process with a new rig, water and environment. If you have any ideas, please help a guy out!

One idea I've put together would be to brew an all base-malt beer (American Wheat, Kolsch, etc) that would remove unfermentable grains from the picture. The idea would be to take a 5 gallons recipe, scale it down to 1 or 2* gallons and then brew it a couple different ways to experiment with process changes. The small size would reduce the cost and pain of a possible drain-pour. I'd probably use a dry yeast to eliminate any smack-pack or starter issues - it'd also help eliminate per-batch changes in pitching rates. I'd also take a 1L sample from each and ferment at 80F to get to attenuation quickly just to give me an idea where the base batch _should_ ferment out to.

A couple of tests:
- #1 base run, no changes
- #2 increase mash time by 30min to 90min (use iodine to ensure conversion**)
- #3 drop mash temp 5F
- #4 leave in primary longer than normal (2 weeks instead of racking off at 85-90% attenuation @ 5-7days)
- #5 ferment in basement @ room temp - perhaps heating/cooling in fridge is capping action?

* any magic to scaling a batch down ? Is 1 gallon too small to brew with the same process ?
** how the heck do you guys get a wort sample with out debris in it for an iodine test ?

Vorlauf before taking the sample. Should help with debris.

Use brewing software to scale to whatever size you want. OR...plain ole math. If you're doing 5 gallons and want to test 1 gallon, take all your numbers and multiply by 0.2.

Make a starter based on the pitching rate calculator from www.mrmalty.com or pitch appropriate amount without starter based on the same calculator.

AERATION

Use a different yeast if that one is not working out for you.

Just some thoughts.

So details I left out:

- aeration is 90s pure O2 in primary
- used 2L starters calculated from the mrmalty calc

As for the brewing software - yeah, I live or die by it

Good thought on the yeast - might be interesting to see same mash/boil with different yeasts too.

leave it on the yeast longer, in fact, dont rack it at all. i think that's the concensus around here, there's ususally no reason for a secondary unless you're dry hopping or adding fruit.

Check your thermometer at mash taps. You might be mashing 5-10 degrees too high

You should try the fast ferment test (http://braukaiser.com/wiki/index.php?ti ... rment_Test) which gives you the attenuation limit of the wort you produced. Once you know that you know if the problem is in mashing (low attenuation limit), fermentation (ok or high attenuation limit but low final beer attenuation) or both (low attenuation limit and large difference between that limit and beer attenuation).

I do this test for all my beers and it is one of the most useful tests you can do that’s out there. Nothing beats knowing where your FG will be 3-4 days after brewing.

Kai

(still trying to fix my avatar)

You didn't give too many particulars for your process. Lower your mash temp 5deg from what?

There are just too many factors to just give an answer. Something in your process is causing your yeast to stop early. Could be high mash temp, or too much crystal or other unfermentable grain in your grain bill, or no O2 in the wort when you pitch, or fermentation temperature fluctuations are causing the yeast stop early, or you are fermenting too cool, or not long enough or.......

If you haven't already check out these two Brew Strong episodes. They should answer a lot of these questions. We might be able to help refine the solution once we have a better idea of your process. Don't go crazy trying to invent tests. Just look at your entire process and then compare that to the processes described in books like Brewing Classic Styles and How to Brew (available on line). I'm sure that by doing a step by step comparison something will jump out at you as "off".

Attenuation
Yeast Starters

I hope something here was useful. Check out some of this stuff and come back. This is a great place to get troubleshooting help!

I've already gotten through those 2 episodes - quite good information. The length of primary fermentation seems to be the biggest difference - although Palmer in How To Brew does say 2-6 days for racking into secondary in 8.4 - seemingly contradicting the 2weeks in primary info.

The recipe was 11.25lbs Golden Promise, 1.75 lbs Caramunich and .25lbs Crystal 55L. Mash temp was 153F - the thermometers were checked at the start of brewing against a calibrated one and an electronic probe thermometer. Fermentation temps were 69F - 71F - I've got a dual stage controlled fridge to keep things right down the middle. I used 90s of pure O2 through a diffusion stone in the primary, where I pitched a 2L starter (20hrs active). I had transferred to the secondary after 6 days once the airlock activity had slowed to about 1 per minute.

This is a good idea- even doing it now with fresh yeast should help me find out if I just have a stuck fermentation or if I mucked up something in the mash. I'm going to start doing this for my future brews as well. It'll give me something to check instead of poking at the primary fermenter

i think palmers advice on racking is outdated and now he recommends leaving it on the yeast cake longer. racking a regular beer is a waste of time and effort, also increases chances of infection.