92% efficiency with batch sparging...

So for a while now, I've been way overshooting my OG by about 10 points, and I don't know why. It never really bothered me before, but I'm trying to get more serious about style guidelines and would like to stay within them. I've been doing Bobby_M's double batch sparge method just as he states. Last week I did an Oktoberfest beer that was supposed to be about 1.052 and it ended up being 1.064. That was measured before pitching the yeast.

So this week before I brewed, I thought I would make sure that my kettle volume was calibrated, and it was. I did a light beer that was supposed to be about 1.048. My preboil, cooled gravity was 1.050. I collected 12.75 gallons. That has my efficiency over 90%. My gravity after boil was 1.059 and that is way too high for this type of beer. I don't know what I'm doing wrong, or am I doing everything right, getting an awesome efficiency and just need to put that into beersmith so it can adjust my grain bill? Any feedback is appreciated.

Just plug your calculated efficiency into future recipe calculations and let beersmith do the math. You'll just have to scale back the base malts. eg try 8 or 9 instead of 10lbs.

There is really no reason to try to scale back your efficiency unless you are having other problems - eg frequent sparge issues.

Wow! That's HIGH!
Like said, if you efficiency is constent around 90%, just calculate your reciepe with this rate.

That said, 2 things.

1-What is that double batch sparge method?
2-It's 1.064, and not 1.64. Because 1.64 is a friggin' heavy thick syrup. Just saying.

Thanks for the correction. I forgot all of my zeros! The Double Batch sparge: after you collect your first runnings, you dump half of your sparge water in your mash tun, mix it up real good, then vorlauf and collect, then repeat with the second half. Doesn't take long and as you can see it is efficient.

Will try it for sure!

Using your pre-boil gravity you should be able to know what volume of beer you need to hit your target gravity. Basic c1 x v1 = c2 x v2 formula where c is concentration (gravity points is our unit), and v is volume. So if your preboil gravity is 1.050 and you have 12.75 gallons, and your target is 1.048, your final volume should be 13.3 gallons (after boiling). You need to add a lot of water before you boil, assuming your calculations are correct...I'm having trouble accepting that high of an efficiency and think it's more likely that there is an error somewhere. Also, I would be concerned to have an efficiency that high, since you are running the possibility of extracting tannins and ending up with a husky and grainy beer.

dbsmith- Those calculations make sense, and I too am skeptical that I am getting such high efficiency numbers. I use beersmith and calculate all of the water I need beforehand so that I don't end up with 13 Gallons of beer (of course its only a problem because my buckets can't hold enough).

My thought is that either my volumes must be off somewhere...or I really am getting that efficiency. Bobby_M states in his "All Grain Primer" that this method will get him 88%-92% efficiency consistently.

Here are my volumes/procedures:

Mash in with 1.25qts/lb which came to 6.5 Gallons of 180 degree water. Let sit in the mash tun until the temp dropped a bit. Added the grain and measured temp after 5 minutes. The temp was still high so I added about .5 Gallons of very cold water which brought the temp to 150. I was happy with that so I left it mash for 75 minutes.

first collections were 2.5 Gallons, put right into the kettle. Dumped about 5gallons of 180 water into the tun, mixed well, vorlauf and drained. Got about 4.5 Gallons from that. Then dumped another 5 gallons in and got 3 gallons (stuck sparge). Dumped 3 more in and drained until my kettle said I had 13.0 Gallons. Mixed it up really well and took a sample, cooled it to ~60 and took my reading of 1.050. Boiled for 90 minutes, cooled wort, put into fermenters. Gravity reading at 73 degrees was 1.059. I never bothered to correct that for temperature, as I was already way off.

Here's how I calculated my efficiency:
0.50 lb Rice Hulls (0.0 SRM) Adjunct 000000
16.00 lb Pilsner (2 Row) Ger (2.0 SRM) Grain 37pts x 16 = 592
2.00 lb Rye Malt (4.7 SRM) Grain 29pts x 2= 58
1.00 lb Caramel/Crystal Malt - 10L (10.0 SRM) Grain 35pts x 1 = 35
0.50 lb Cara-Pils/Dextrine (2.0 SRM) Grain 33pts x .5 = 16.5

Total pts 701.5/13G (volume collected pre-boil) = 53.96

preboil OG 50/53.96 = 92%

I need to calibrate my kettle one more time just to make sure that is not the issue because that is the only place that I can see a problem. How about you guys? How accurate are the measurements on the side of the fermenting buckets? I used the bucket to jump up to 5 Gallons, then used my 1 Gallon pitcher to go the rest of the way. Thanks!

Are you weighing your grains correctly? When I hit really high eff it usually turns out to that little extra pinch of 2 row I add. I'm not sure how accurate those buckets are.

Also there's nothing wrong with diluting post boil to hit your correct OG. Plus more beer!

The best I get is 72-74 and batch sparge using the same method, not sure how you are getting above 90%

If you figure it out, holler as inquiring minds would like to know

Toy4Rick

TGmartin....That is one variable I never took into account! Great thought. I always get my grain pre-measured from my LHBS, and they crush it and put it in one bag for me...therefore I've never bothered to weigh it again. Maybe they are giving me a bit more than I asked for?

So for my next batch which may be in the next few weeks, I need to re-weigh my grains, and take the time to very accurately calibrate my kettle sight glass. do you guys see any other variables that I need to look at?

Toy4Rick said:

The best I get is 72-74 and batch sparge using the same method, not sure how you are getting above 90%

If you figure it out, holler as inquiring minds would like to know

Toy4Rick

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I get 80%-92% and I batch sparge. The range is determined by grain bill size, but since getting my own mill, I haven't gotten less than 80%, even with a 22lbs. bill.

I've tried double batch sparging a few times, but never saw more than a 1-2% increase in efficiency. well within the margin of error for measurement. For me it isn't worth the time or effort.

Your calculations seem solid, so either it is your measuring or you just somehow have really high efficiency. Here are some things to check:

-Stir your preboiled wort a bit before sampling to make sure you aren't only reading from the more concentrated bottom part of the pot.
-Verify your grain weight
- How does your crush seem?
- Verify your volumes

If the high efficiency is bothering you, try just a single sparge, or even a 1.5 sparge method, drop the sparge temperature a bit, or just dilute the wort if you have the space using that c1v1 = c2v2 equation. Good luck!

I didn't notice if anyone mentioned it, but if you use an average ppg for the grain but the particular lot is higher, then you can end up with artificially inflated efficiency numbers.

BTW, sparge temp will not directly affect efficiency.

DBsmith...thanks for the feedback. FYI, I took the pre-wort sample from the top of the kettle after a quick stir...I will be sure to stir a bit better next time to rule that out. Crush seems great, some powder but not a ton. I will definitely verify the weight before mashing, and will re-verify the volumes. Thanks for the help.

Denny, that is a good point you make. Is there a way to know what the ppg of a particular batch is?

Thanks again guys.

digphish said:

Denny, that is a good point you make. Is there a way to know what the ppg of a particular batch is?

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When you (or your supplier) buy a bag of malt, there should be a tag attached with the lot number. Theoretically, you can then go to the website of the maltster and get the info on the extract yield for that lot. Unfortunately, that info isn't always available.