I am baffled on this one. Whenever I try to brew a beer destined to be at least 7% I have HORRIBLE efficiency problems. Yet, when I try to a brew a beer between 5-6% I hit my target OG to the point. Some recent examples: Double IPA, Expected OG 1.073, Actual OG 1.052 Robust Porter, Expected OG 1.083, Actual OG 1.066 Saison, Expected OG 1.056, Actual OG 1.056 Saison (same recipe as above brewed a month later) Expected OG 1.056, Actual OG 1.056 Imperial Stout (brewed last night), Expected OG 1.100, Actual OG 1.077 Here is a detailed description of my stout brew: Recipe formulated using Beersmith 20lbs of grain total divided into 2 identical 10lb bags. I have to do 2 separate mashes since my mash tun is only 5 gallons. Mash 1- 60min @153 degrees (10lbs of grain/3 gallons of water). First runnings were reading 1.080 so I let the mash go another 30 minutes. After 90 minute mash first runnings were reading 1.091. Batch sparged with 4 gallons of 168 degree water, stirred very well, let sit 20 minutes before collecting the 1.040 second runnings. At this point I got the wort I had collected so far in the kettle and starting bringing the temp up. I figured I should start reducing it now since the OG is already so low. First and second runnings combined for an OG of about 1.055. Mash 2- tried a higher mash temp and a thinner mash to see if it would improved efficiency. Mashed at 158 for 90 minutes with 4 gallons of water and 10lbs of grain. This produced first runnings of about 1.070. Even lower than the first mash! I added the first runnings of mash 2 to the wort I already had collected in my kettle which brought the overall temperature of the wort to 175. I cooled the wort to 168 and then batch sparged with the 168 degree wort rather than using sparge water hoping to raise the gravity as much as I could (idea inspired by Pretty Things double mash technique). All in all, I had a pre boil OG of about 1.060. Extended my boil to 2 hours instead of the intended 90 minutes, added some brown sugar, and ended up with an OG of 1.077. About 20 points shy of my expected OG which seems to fit into the pattern of being about 20 points too low for all of my big beers. But why aren't my saisons coming in at 1.036 instead of 1.056? Same equipment, my temperatures are always locked in, grain is always crushed in the same mill on the same setting in the same home-brew store. Really hope someone can help clear my confusion.
I've only been brewing for a year, so take my advice with a grain of salt. Hopefully you get some more thorough responses (and maybe I'll get some clarification too) Why did you use different amounts of water on the separate mashes? You said 10 # grain with 3 gal water in the first, and 10 # grain with 4 gal water in the second? Using different amounts in each would mean you would have to readjust your sparge water calcs for each mash -- but you said you did a "double mash" on the second? You'd have 1.2 qt/lb in the first, and 1.5 qt lb in the second. I'm leaning towards this being the reason your numbers are off. That seems overly complicated. Also, when you sparge with wort, you reach a saturation point of how much sugars the liquid can actually hold. I'm not sure if this is even worth it, but that's just something I had read -- I'll let others chime in on that more. Are your two separate mash tuns identical? A big part of efficiency is knowing your equipment to a T so that you can plug in accurate values into your software/calcs. If you're using two completely different mash tuns and want exact numbers, youd have to half the recipe and essentially create two recipes for each one (again, massive hassle and headache) Since you're saying this is a common theme with big beers, I'd guess that the issue is using two separate mash tuns for grain and differing amounts of water in each. If your small beers all fit in just one mash tun, and come out right on target, I'd think this is the culprit. Do you think that might have something to do with it? (Also, just a heads up, we built a DIY rubbermaid mash tun for like $50 total... might be worth looking into)
What's your typical efficiency? And how tightly packed are the bags? Raising the mash temp won't improve efficiency. Check your thermometer calibration and get a bigger cooler.
thanks for the replies. I have one 5 gallon mash tun. I did 1 mash+sparge, emptied and cleaned the tun, then did mash number 2. I used more water at a higher temp in the second mash to see if a hotter and thinner mash gave a better conversion (which it did not). I was really just trying something different since the first mash (3 gallons for 10lbs of grain) gave such an underwhelming OG. My efficiency is normally around 70% (for smaller beers)
Big beers call for more grain; however ... your boil volume / batch size remains the same. This means you end up leaving more sugar behind (i.e., lower efficiency) than you do when brewing lower gravity recipes. Soln: collect and boil more wort.
One thing that could help is removal of the specialty grains, which don't require mashing; since you've not posted grain bill, I'm making an assumption. If you pull the pounds of grains out that don't need to be mashed, you'll be able to do a thinner mash, which I believe is the underling reason for low efficiency. I see you tested thinner mash on mash 2 vs. mash 1. However, 1.2 seems thick.
Yeah, it basically comes down to what @HerbMeowing said. I brewed a 1.081 Scotch Ale yesterday. I collected 7.5 gallons of 1.054 wort. 2.5 hours later, I had boiled it down to 5.25 gallons and hit 1.081 on the nose. My efficiency is typically 78%. Yesterday I was around 72%. I'd really recommend you get a bigger mash ton. Adding another 60-90+ minutes to basically mash the same beer twice is the last thing I want to do on my brew day. Also, 70% is on the lower end for efficiency (though still pretty good for BIAB) for a 'standard' OG beer. If it works for you, great, but like I said, I'd rather save myself the time.
This is exactly right. kevindwyer, what you describe is the classic case of expecting the impossible. When you make a bigger beer, your efficiency will fall unless you help improve it by collecting more runnings and boiling much longer. Otherwise if you don't want to do that and just want to continue with a standard 60 or 90 minute boil, then you need to expect that your efficiency will fall for bigger beers. I ran all your numbers in a little Excel spreadsheet and here's what I came up with: For smaller beers, you are getting efficiencies in the low to mid 70s, which is great. But then for bigger beers you are doing nothing very different (except maybe for that impy stout) but still expecting efficiency in the 70s, whereas your efficiency is actually dropping to about 60% for beers above 1.070 and to 50% for beers above 1.080. In future, just figure your efficiency will fall way back for bigger beers as I have outlined, therefore you'll need to use a little more grain, and maybe collect more runnings and plan to boil a little longer than normal, and you'll start to nail your intended OGs again. I'm pretty sure every all-grain brewer on earth runs into this issue as soon as they start making really big beers, and the fixes are always the same: assume lower efficiency, and consider boiling longer. You can add extract too, but... that's cheating!
This is what some fairly big breweries do if they can't get enough grain into the mash tun. If you tour a brewery and see 50 Lb. bags of DME, you can bet those are not used for homebrew.
