Reasons not to brew high gravity and dilute?

[mac_1103]

So I BIAB with a ten gallon kettle. Planning to do a pair of ~6.5% ABV SMaSH pale ales (one citra and one mosaic). Is there any reason not to mash as if I was brewing 5 gallons of a 1.1 gravity ale and then split the batch and dilute before boiling and hopping?

 

[fluketamer]

hey mac,

no i dont think so but i dont do it and have only done a handful of large AG batches .

but i think i read on here that the big commercial breweries do it like anheuser busch

let us know

 

[BrewnWKopperKat]

Things to consider (vs reasons to not do it):

• Mash efficiency is likely to be lower with the high gravity mash.
• Might be some oxygen-related considerations when diluting the wort to achieve pre-boil SG.

 

[Mr. Vern]

Other than slight loss of efficiency and potential PH adjustments this would work fine.

Maybe keep some extract handy if you need/want to boost gravity.

 

[Brew_Dude41]

I mean dumb question, but will you be able to hold enough grain and water to extract 5 gallons of wort @ 1.1 sg?

 

[pvpeacock]

I used to make 10 gallon batches by making 7 gallons of high gravity wort (the most my old brew kettle would hold) and then diluting it to top off 2 fermenters with 5 gallons each. I never had a problem.

 

[Mr. Vern]

A quick look and I think @Brew_Dude41 has a point. You'll need 20 Lbs of grain which will take up 6-ish gallons by itself.

I could do it in my Keggle, but I think it is a challenge with a 10 gallon single kettle.

 

[mac_1103]

I mean dumb question, but will you be able to hold enough grain and water to extract 5 gallons of wort @ 1.1 sg?

I'm thinking just barely if I mash fairly thick. Might not be worth the trouble just to be able to say that I made two beers from the same wort with different hops.

 

[Bobby_M]

Efficiency loss is the main reason, and may be a deal breaker for you. When your wort gravity is twice as high, so are your sugar losses to grain absorption. In other words, if you lose 1 gallon of 1.100 wort, it's worse than losing 1 gallon of 1.050 wort.

 

[Peebee]

Why has no-one said "parti-gyle".? Brewers have been doing it since year dot.

But the question is reasons not to:

Once the wort is in the boiler, I just can't bring myself to watering it down ... but I think the issue is one of psychology not brewing hazards. I've never considered "efficiency" or anything like that being a serious problem, though "parti-gyling" ... that's for weirdos.

(The "split and hop differently" bit holds no penalties I can think of. Except you might prefer one over the other and kick yourself for wasting the time doing the one you don't like).

 

[doug293cz]

For 5 gal in fermenter batches that will yield 6.5% ABV you will need 10 gal of ~1.060 OG wort. Assuming a low boil-off of 1 gal per 5 gal batch you will need 12 gal of wort at 1 + 0.060 * 10 / 12 = 1.050 pre-boil SG. That would require 6 gal @ 1.100 pre-boil, or 5 gal @ 1.120 pre-boil.

Assuming you routinely get 100% conversion efficiency, and a consistent grain absorption rate of 0.07 gal/lb, then for:

6 gal @ 1.100 SG pre-boil, then numbers look like this:​

Grain = 26.7 lb​

Strike Vol = 7.87 gal​

Mash Vol = 10.0 gal​

Mash Thickness = 1.18 qt/lb​

Mash Efficiency = 63.6%​

​

5 gal @ 1.120 SG pre-boil, then number look like this:​

Grain = 30.26 lb​

Strike Vol = 7.12 gal​

Mash Vol = 9.5 gal​

Mash Thickness = 0.94 qt/lb​

Mash Efficiency = 56.3%​

​

Your task won't be easy. If you get less than 100% conversion efficiency, or higher than 0.07 gal/lb grain absorption, then the numbers will be even worse.

Calculations done with my mash and lauter simulator.

Brew on

​

​

 

[doug293cz]

Efficiency loss is the main reason, and may be a deal breaker for you. When your wort gravity is twice as high, so are your sugar losses to grain absorption. In other words, if you lose 1 gallon of 1.100 wort, it's worse than losing 1 gallon of 1.050 wort.

And you lose even more because you have more grain absorbing wort, so the fraction of the total wort absorbed by the grain will be higher.

Brew on

 

[Red over White]

For 5 gal in fermenter batches that will yield 6.5% ABV you will need 10 gal of ~1.060 OG wort. Assuming a low boil-off of 1 gal per 5 gal batch you will need 12 gal of wort at 1 + 0.060 * 10 / 12 = 1.050 pre-boil SG. That would require 6 gal @ 1.100 pre-boil, or 5 gal @ 1.120 pre-boil.

Assuming you routinely get 100% conversion efficiency, and a consistent grain absorption rate of 0.07 gal/lb, then for:

6 gal @ 1.100 SG pre-boil, then numbers look like this:​

Grain = 26.7 lb​

Strike Vol = 7.87 gal​

Mash Vol = 10.0 gal​

Mash Thickness = 1.18 qt/lb​

Mash Efficiency = 63.6%​

​

5 gal @ 1.120 SG pre-boil, then number look like this:​

Grain = 30.26 lb​

Strike Vol = 7.12 gal​

Mash Vol = 9.5 gal​

Mash Thickness = 0.94 qt/lb​

Mash Efficiency = 56.3%​

​

Your task won't be easy. If you get less than 100% conversion efficiency, or higher than 0.07 gal/lb grain absorption, then the numbers will be even worse.

Calculations done with my mash and lauter simulator.

Brew on

​

​

I've brewed batches larger than my boil kettle for a long time. Doug lays out the efficiency above. I adjust the hop additions and dilute in the fermenter with distilled water. The high gravity macro approach, but diluting into the fermenter and not at package to avoid the yeast issues with higher alcohol headaches and pronounced esters. The beer quality is exactly the same with an economy of available undersized equipment and cooling of wort more efficiently.

 

[doug293cz]

Why has no-one said "parti-gyle".? Brewers have been doing it since year dot.

But the question is reasons not to:

Once the wort is in the boiler, I just can't bring myself to watering it down ... but I think the issue is one of psychology not brewing hazards. I've never considered "efficiency" or anything like that being a serious problem, though "parti-gyling" ... that's for weirdos.

(The "split and hop differently" bit holds no penalties I can think of. Except you might prefer one over the other and kick yourself for wasting the time doing the one you don't like).

You wouldn't actually do a parti-gyle, you would do a batch sparge (dunk sparge for BIAB) and blend the first runnings and sparge runnings to get two 6 gal fractions that had the same SG.

Using the same conversion efficiency and grain absorption numbers as my previous example, then numbers look like this:

Grain = 22.7 lb​

Strike Vol = 7.6 gal​

Mash Vol = 9.4 gal​

Mash Thickness = 1.34 qt/lb​

First Runnings Vol = 6.0 gal​

Sparge Vol = 6.0 gal​

Sparge Runnings Vol = 6.0 gal​

Mash Efficiency = 89.3%​

Blending would be easier if you had two 7+ gal vessels in addition to your 10 gal pot.

Brew on

 

[mac_1103]

Blending would be easier if you had two 7+ gal vessels in addition to your 10 gal pot.

Yeah, that's another complicating factor. I have two five gallon pots and plenty of 5 to 6.5 gallon buckets. I mean, I could probably make it work if I sparge cold, but it would sort of defeat the whole purpose if I didn't get the blend right. Diluting in the fermenter might be easier.

Thanks to all for the comments and suggestions.

 

[Peebee]

You wouldn't actually do a parti-gyle, you would do a batch sparge (dunk sparge for BIAB) and blend the first runnings and sparge runnings to get two 6 gal fractions that had the same SG.

...

Yeap, I've made that mistake and had to be corrected for it.

"Parti-gyle" only means start out making one beer and end up with two or more different beers.

In this case make the same beer but split and boil with different hops. Could be make same beer and split and dilute each to different strengths. Or it could be crazy complicated, however you please. Fuller's (London) beers was the one I was fed as an example.

[EDIT: Oh aye. And Guinness stout is possibly another. Brewed at ABV somewhat over 7%, diluted to 4.? for their "extra stout", possible used for others in their range. And ... they split before the mash! The roast barley is "mashed" separate from the pale malt and blended as required.]

 

[doug293cz]

Yeap, I've made that mistake and had to be corrected for it.

"Parti-gyle" only means start out making one beer and end up with two or more different beers.

In this case make the same beer but split and boil with different hops. Could be make same beer and split and dilute each to different strengths. Or it could be crazy complicated, however you please. Fuller's (London) beers was the one I was fed as an example.

[EDIT: Oh aye. And Guinness stout is possibly another. Brewed at ABV somewhat over 7%, diluted to 4.? for their "extra stout", possible used for others in their range. And ... they split before the mash! The roast barley is "mashed" separate from the pale malt and blended as required.]

Normally, parti-gyle is used to describe when you make one strong beer, primarily from the first runnings, and one (or more) weaker beers from primarily the sparge runnings. Blending is common, but not to a single strength. If you only have a single SG wort prior to boil, it's just a normal sparge operation.

Brew on

 

[mashdar]

Yeah, that's another complicating factor. I have two five gallon pots and plenty of 5 to 6.5 gallon buckets. I mean, I could probably make it work if I sparge cold, but it would sort of defeat the whole purpose if I didn't get the blend right. Diluting in the fermenter might be easier.

Thanks to all for the comments and suggestions.

Have you tried a cold sparge? I can hardly tell the difference between 70F vs 170F, other than time to boil.

 

[mac_1103]

Have you tried a cold sparge? I can hardly tell the difference between 70F vs 170F, other than time to boil.

Guess I could have been clearer. I cold sparge often. That's not the issue. It's messing up the blending and winding up with two different OG worts that would defeat the whole purpose of doing it this way.

At any rate, I'm leaning toward thinking that I don't want to take the efficiency hit that this would entail. I suppose an alternative would be to do two separate mashes back-to-back and adjust the pre-boil volumes and gravities to match. But that would make for a really long brew day. So I'll probably just do two separate brews and hope that I don't do anything to screw up the reproducibility of the process.

 

[sibelman]

Given your goal, @mac_1103 , your simplest path would be to split the strong wort into two smaller batches for separate fermentation. Instead of struggling to exceed what your system can reasonably do.

Sorry to belabor the obvious.

 

[mac_1103]

Nope. Give me five gallon batches or give me death!

 

[sibelman]

Give me five gallon batches or give me death!

I brewed less than 5 gallons once. Didn't like it, didn't inhale.

Do you have similarly extreme feelings about adding DME or sugar to get to the gravity you want? This would maintain one-boil two-fermentations purity. And take much less time and effort.

 

[mac_1103]

Do you have similarly extreme feelings about adding DME or sugar to get to the gravity you want?

Not at all. I may be dogmatic, but I'm not proud. Guess it wouldn't really be a SMaSH if I did that though.