How important is runoff gravity?

[bstacy1974]

I've read posts within this forum talking about how your runoff gravity needs to be around 1.020. My runoff gravity is consistently in the 1.030 to 1.035 range, with batch sparging.
I achieve my volumes without issue and usually come within a point or two of all my other gravity measurements.
So, am I missing something with a high runoff gravity?

 

[schematix]

low gravity is the issue. generally indicating over sparging and pH likely to get out of range.

 

[bracconiere]

i fly sparge, but usually just go by color of the runoff....and of course my BK is only 15 gallons big so i'll just slow it down.....

 

[Vale71]

So, am I missing something with a high runoff gravity?

Yes, you're missing all the extract you're leaving behind in the spent grain. It's basically an extraction efficiency issue. In a non-commercial context you might just decide that you don't care, if you're trying to make a living out of it it could be what makes your operation go bust and leave you without a job.

 

[bracconiere]

Yes, you're missing all the extract you're leaving behind in the spent grain. It's basically an extraction efficiency issue. In a non-commercial context you might just decide that you don't care, if you're trying to make a living out of it it could be what makes your operation go bust and leave you without a job.

kinda what i wanted to say...but i know brewing cheap beer is shunned here.....

 

[doug293cz]

I've read posts within this forum talking about how your runoff gravity needs to be around 1.020. My runoff gravity is consistently in the 1.030 to 1.035 range, with batch sparging.
I achieve my volumes without issue and usually come within a point or two of all my other gravity measurements.
So, am I missing something with a high runoff gravity?

Are you doing single batch sparging, fly sparging, or what? For a single batch sparge of a 5.5 gal (end of boil) batch, using 10 lb of grain, your first runnings should be around 1.070, your sparge runnings should be around 1.025, pre-boil about 1.048, and post-boil (OG) about 1.056. If you are doing bigger beers, then the sparge runnings will be higher SG than the above. If you are not doing bigger beers, then your lautering process is inefficient. Fly sparging should be more efficient than batch sparging (final runnings SG lower.) If it is not, then your process has issues, and you are wasting time and effort fly sparging.

The above is not really something to obsess about if you just want to make and enjoy your beer. But, if you are one of those brewers who wants to know they are running their process the best they can, then you can worry about it. Depends on what you want out of your hobby.

Brew on

 

[bstacy1974]

I am trying to be more efficient. Grain is expensive where I live and I'm trying to get the most beer for my money.

I am single batch sparging.
My set up is a 10 gal boil kettle and 10 gal cooler, with a RIMS tube. I mash in a bag in the cooler.

After the mash, I run off to the kettle, dump in the sparge water, and recirculate for 10 mins to clear. I then run the sparge to the kettle. Once I have my preboil volume in the kettle, I move my mash tun to another part of my garage. I hang the bag from a nail while still keeping it in the cooler. I'll end up with another half gal or more of wort that drains from the bag before I start cleaning up.

Tonight's brew was a typical American IPA with 12lbs of grain. I estimate 75% efficiency in Beersmith when creating recipes.

Second running was 1.035, as mentioned previously. Preboil gravity was 1.053. OG was 1.060. Mash volume was 4.75 gals of water. Sparge volume was 3.5 gals. Mash temp was 154F. Boil volume was just under 7 gals. Volume to the fermenter was about 5.5, or just slightly more. I easily leave 0.5 gal in the boil kettle so lots of the hop debris and trub stay out of the fermenter. I also estimate about a 0.5 gal loss in the fermenter.

After most brew days, I feel there must be a way for me to be more efficient, but I'm at a loss as to where it is in my process.

 

[Vale71]

If I understand you correctly then you're actually using a no-sparge technique so the whole concept of last runnings gravity does not even apply.

 

[bstacy1974]

If I understand you correctly then you're actually using a no-sparge technique so the whole concept of last runnings gravity does not even apply.

No, I am sparging. Tonight, for example, I mashed with 4.75 gals for an hour. Drained the wort to my kettle, then sparged with another 3.5 gals water.

 

[bstacy1974]

No, I am sparging. Tonight, for example, I mashed with 4.75 gals for an hour. Drained the wort to my kettle, then sparged with another 3.5 gals water.

Sorry, I'm quoting myself. I didn't have an edit option on my phone.
I should clarify, my first running after mash during tonight's brew was barely over 3 gals.

 

[Vale71]

My bad, I thought you only had the 2 vessels and were heating the "sparge" water in the boil kettle and then addiing it to the mash before draining. Basically you're doing a batch sparge with one single batch.

 

[madscientist451]

I am trying to be more efficient. Grain is expensive where I live and I'm trying to get the most beer for my money.



Second running was 1.035, as mentioned previously. Preboil gravity was 1.053. OG was 1.060. Mash volume was 4.75 gals of water. Sparge volume was 3.5 gals. Mash temp was 154F. Boil volume was just under 7 gals. Volume to the fermenter was about 5.5, or just slightly more. I easily leave 0.5 gal in the boil kettle so lots of the hop debris and trub stay out of the fermenter. I also estimate about a 0.5 gal loss in the fermenter.

Time is also a valuable commodity, but if you have free time and want to experiment you could try this:
-Perform an evaporation test with your kettle to determine how much water boils off in 30 minutes.
-Brew the same beer as above, but reserve 1/3 of the first runnings in food safe bucket (if you don't have another kettle).
-Run off second runnings to get your boil volume+ enough to boil 30 minutes longer.
I'm not running the calculations, but you should be somewhere near your desired post boil gravity if you increase your boil time.
-Add more batch sparge water a gallon at a time and monitor the gravity, and quit when you get to 1.020 (but you could probably go lower if you want to be really cheap, but I wouldn't go below 1.010)
-Combine the third runnings with your reserved first runnings and now you've made a second beer out of the same grain. You could bring the ABV up with some sugar if you want to. (is sugar more or less expensive than grain in your location?)
So you can see this will basically double (or more) the time you spend on your brew day and you'll have to decide if its worth it. The second beer won't be as good as the first run beer, but it will still be beer. You could experiment further by blending the two brews and tweaking boil times.
Another option is to just make a 100% third run beer and see how it comes out.
I've done this, and its ok, but its better if you add in some of the first runnings when I've tried it.
If you want to be a super frugal and if you use late addition/whirlpool hops in the first beer, don't toss out the kettle hop sludge from the first beer, dump the third runnings on top of it and boil as usual. There's still lots of unused bitterness in those whirlpool hops. If you really use a lot of hops, it may be better to dump the sludge off to a bucket and then add back what seems like an appropriate amount.

 

[Yooper]

Once you add your sparge water, are you stirring it well? I know you recirculate, but stirring it well and then recirculating to clear and then running off works more efficiency.

 

[seatazzz]

This is kinda what I do, and I'm using basically the same setup as OP. My sparge runnings are usually in the 1.030-1.035 range, depending on the grain bill, and I don't do a third sparge. What I've been trying to do lately is get a better estimate of my preboil volume with just the first runnings and the sparge, with an eye to a 90 minute boil. After the sparge is out of the tun, I pull up the bag and let it drain while the BK is heating up; if my volume is around 8 gallons, I'll add what I call the "dead space" wort from the tun to the BK once the bag is drained completely. That gets my volume up to where I need it, and helps my efficiency. And no I don't squeeze the bag.

 

[doug293cz]

I am trying to be more efficient. Grain is expensive where I live and I'm trying to get the most beer for my money.

I am single batch sparging.
My set up is a 10 gal boil kettle and 10 gal cooler, with a RIMS tube. I mash in a bag in the cooler.

After the mash, I run off to the kettle, dump in the sparge water, and recirculate for 10 mins to clear. I then run the sparge to the kettle. Once I have my preboil volume in the kettle, I move my mash tun to another part of my garage. I hang the bag from a nail while still keeping it in the cooler. I'll end up with another half gal or more of wort that drains from the bag before I start cleaning up.

Tonight's brew was a typical American IPA with 12lbs of grain. I estimate 75% efficiency in Beersmith when creating recipes.

Second running was 1.035, as mentioned previously. Preboil gravity was 1.053. OG was 1.060. Mash volume was 4.75 gals of water. Sparge volume was 3.5 gals. Mash temp was 154F. Boil volume was just under 7 gals. Volume to the fermenter was about 5.5, or just slightly more. I easily leave 0.5 gal in the boil kettle so lots of the hop debris and trub stay out of the fermenter. I also estimate about a 0.5 gal loss in the fermenter.

After most brew days, I feel there must be a way for me to be more efficient, but I'm at a loss as to where it is in my process.

Ok, I plugged your numbers into my mash & sparge simulator, and come up with a pre-boil SG of 1.053, and an OG of 1.060! Mash efficiency was 85%. This is about as good as you can do with a single batch sparge, and typical grain absorption rate for a mash tun.

The odd thing is that for the simulation, I got a second (final) runnings gravity of 1.030, not 1.035. Some things that could cause second runnings to be higher than expected:

1. Conversion was incomplete at the time of initial run-off, and you got some additional conversion during the sparge rest.
2. Undrainable volume in the MLT, which will cause more sugar to remain in the MLT after initial run-off, thus having more sugar in the second run-off.
3. Not draining long enough during first runnings, so that wort volume retained in the MLT is higher than expected.
4. SG measurement errors.

I suspect you may have had a combination of the first three above, and maybe #4 as well, but since #1 offsets some of the effect of #2 & #3, your overall mash efficiency was not strongly affected.

Some things you can do to maximize mash efficiency:

1. Insure that you have close to 100% conversion efficiency. You can use the method here to monitor conversion efficiency during the mash, so you can then extend the mash time to improve conversion efficiency, if necessary. For example, the end of mash wort SG for your example should have been 1.078 @ 100% conversion.
2. Minimize (eliminate) MLT undrainable volume.
3. Reduce the grain absorption rate by squeezing the bag. Squeezing is more effective after initial run-off vs. after sparge run-off. For example your absorption rate appears to be near the typical MLT rate of 0.12 gal/lb. A reduction to 0.09 gal/lb would have increased your mash efficiency to 88%, and your OG to 1.062. Even more aggressive squeezing to a 0.06 gal/lb rate would get 91% and 1.065.
4. Go to a double batch sparge. Without squeezing, this would increase your mash efficiency to 88%-89%, and OG to 1.063. Add the aggressive squeeze, and you could get to 94% and 1,067. For a double batch sparge, mash in at a 1.25 qt/lb ratio, and then evenly split your remaining brewing water between the two sparge steps.
   
5. Go to a fly sparge, which if done well, would get you better results than a double batch sparge.

You also want to minimize kettle to fermenter and fermenter to bottle/keg volume losses. Your "transfer efficiency" is about 5.5 gal / 6.0 gal = 92%, making your brewhouse efficiency 85% * 92% = 78%.

Brew on

 

[doug293cz]

Once you add your sparge water, are you stirring it well? I know you recirculate, but stirring it well and then recirculating to clear and then running off works more efficiency.

Lack of adequate stirring is more likely to result in unexpectedly low sparge runnings SG, not unexpectedly high SG, so I don't think lack of stirring is a factor in OP's issue.

Brew on

 

[bracconiere]

Mash volume was 4.75 gals of water. Sparge volume was 3.5 gals.

i skipped a few posts but this to me seems like to thin a mash, and not enough sparge water.......that's close to 1.6qt's/lb grain and not enough rinsing....

i'd say shoot for 1.2-1.3 qts/lb, and sparge more....

something like 2.5 gallons of strike water, and 5 gallons of sparge water....(if i did my quick math right)

well anyway, i do 10 gallon batches with ~21 lb's grain, 7 gallons strike water, and 10 gallons sparge....it seems odd to me that you mash in more water then sparge, to convert you really just need to get the grain somewhat wet/loose...then rinse like a mo-fo....

 

[Blazinlow86]

kinda what i wanted to say...but i know brewing cheap beer is shunned here.....

Nothing wrong with brewing cheap beer if that's your goal. That was my initial reason for starting brewing. Pretty quickly my goal changed to making the best beer possible regardless of costs and I think alot of others that stick with the hobby also end up doing the same. Admittedly I'm very picky with my beer and am fortunate enough to not be tight cashwise so if my homebrew isn't fantastic I just end up drinking the expensive stuff from the store and the homebrew goes to waste. Cheers

 

[bracconiere]

am fortunate enough to not be tight cashwise

when i tell people i make $7.50/hr, most people here tell me they'd rather sit on the street corner....lol

 

[doug293cz]

i skipped a few posts but this to me seems like to thin a mash, and not enough sparge water.......that's close to 1.6qt's/lb grain and not enough rinsing....

i'd say shoot for 1.2-1.3 qts/lb, and sparge more....

something like 2.5 gallons of strike water, and 5 gallons of sparge water....(if i did my quick math right)

Nope. OP is very close to the optimal strike volume to sparge volume ratio to maximize lauter efficiency for a single batch sparge (optimal would have been 4.85 gal strike & 3.4 gal sparge. Efficiency difference between OP and optimal is 0.) Batch sparge lauter efficiency is maximized when all run-offs have the same collected volume. Since grain absorption only affects the initial run-off, the strike water volume needs to be higher than sparge water volume.

Brew on

 

[bracconiere]

Nope. OP is very close to the optimal strike volume to sparge volume ratio to maximize lauter efficiency for a single batch sparge (optimal would have been 4.85 gal strike & 3.4 gal sparge. Efficiency difference between OP and optimal is 0.) Batch sparge lauter efficiency is maximized when all run-offs have the same collected volume. Since grain absorption only affects the initial run-off, the strike water volume needs to be higher than sparge water volume.

Brew on

i've never batch sparged, so i wouldn't know....how about 3 batch sparges then? 2.5 gallons strike, then 2.5 batch sparge, then another 2.5 batch sparge?

 

[doug293cz]

i've never batch sparged, so i wouldn't know....how about 3 batch sparges then? 2.5 gallons strike, then 2.5 batch sparge, then another 2.5 batch sparge?

That's two batch sparges. Yes, the more sparges, the higher the lauter efficiency, but you get into diminishing returns fairly quickly. Here's one of my favorite charts that summarizes the effects of "beer size", sparge count (for batch sparges), and grain absorption rate (i.e. degree of squeezing.)

In effect, a fly sparge is like doing lots of small batch sparges, so a properly conducted fly sparge will have a lauter efficiency a few points higher than the top, solid, green line on the chart. For max efficiency in a fly sparge you want to mash as thick as practical. Turns out with multiple batch sparges, you also end up with the minimum strike water volume being limited by max mash thickness.

Brew on

 

[bracconiere]

i like the simulation by doug293cz part at the....and i'm not sure if you're agreeing with me or not.....lol, so a 2 step sparge would be better?


and i'd have to agree that the way i fly sparge is like a lot of batch sparges, being that i use a collander still, i don't have a constant flow. and don't keep the 2" level above my mash...sometime's it'll drain completly a few times during my sparge...i just do it slowly.

 

[doug293cz]

i like the simulation by doug293cz part at the....and i'm not sure if you're agreeing with me or not.....lol, so a 2 step sparge would be better?

Yes, two sparge steps gives better efficiency than a single sparge step. I already said that here, #4 in the second list in the post.

Brew on

 

[bracconiere]

i skipped a few posts but this to me seems like to thin a mash,

guess that was of the ones i missed....