Help me figure out what went wrong re: efficiency

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robdamanii

robdamanii

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So today I brewed a pretty simple Wit, using 10.5 pounds of grain in my recipe. I have a 10 gallon MLT with a bazooka screen (which I think may be the problem) and I'm fly sparging (albeit with a crappy home made sparge arm.)

My recipe calls for a 6.5 gallon preboil volume. I reached the 6.5 gallons, and when I took a final runnings reading from the flow out of the MLT, it read 1.024 (corrected for temperature.) I ended up using an additional gallon of sparge water to get the runnings down to 1.012, and had to boil off an additional gallon during the boil.

My efficiency for this batch is 78% which is not great, but I can live with it. My OG came out at 1.054, which is a couple points above my target OG. My question is why am I needing more water than prescribed in my recipe calculations just to get the correct OG? Equipment set up or technique?

Thanks!
 
robdamanii said:
This is true, but I'm really not understanding why it took extra sparge water to get there. :confused:
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Because you ended up pulling more sugars out then you had planned for. Meaning you ended up with more volume of wort higher OG than anticipated. Next time you can use less grain.
 
If you stoped at 6.5 gallons like anticipated, you would have been even higher in the OG department. So you let the gravity of the run off drop to reduce the OG of the wort, which means you can use less grain to acheive your target next time.
 
Celticway said:
which means you can use less grain to acheive your target next time.
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I don't know that I'd make that conclusions based on a single brew day. It would suck if this one was an anomaly and by trying to save a few bucks on grain you end up short of your OG or volume on the next batch. I'd probably advise watching for a trend and adjusting based on a pattern, rather than one batch.
 
IffyG said:
I don't know that I'd make that conclusions based on a single brew day. It would suck if this one was an anomaly and by trying to save a few bucks on grain you end up short of your OG or volume on the next batch. I'd probably advise watching for a trend and adjusting based on a pattern, rather than one batch.
Click to expand...

I agree. I was just answering his question.
 
Try sparging slower next time. Your fly sparge technique isn't doing an effective job at rinsing the sugar, which is why you had to use more water than you intended. Most likely because you are going to fast. If you don't want to wait, try batch sparging instead.
 
Celtic is correct. The last gallon pulled @ between 1.024 -1.012 gravity brought the total volume gravity points down.

Rob, try to keep track of your total mash effeciency in the future. (preboil volume/gavity) this will help you understand your equipment setup a little better and what you can expect from it.

Problem here is, you're going to have to brew more beer to get more data :), I know that sounds terrible...
 
WHYB said:
Celtic is correct. The last gallon pulled @ between 1.024 -1.012 gravity brought the total volume gravity points down.

Rob, try to keep track of your total mash effeciency in the future. (preboil volume/gavity) this will help you understand your equipment setup a little better and what you can expect from it.

Problem here is, you're going to have to brew more beer to get more data :), I know that sounds terrible...
Click to expand...

Lol. Yeah I hate having to brew more!
 
WHYB said:
Celtic is correct. The last gallon pulled @ between 1.024 -1.012 gravity brought the total volume gravity points down.
Click to expand...

No that is not correct. If you sparge longer you get more sugar in your kettle and your final post boil gravity will be higher. Assuming you boil longer to boil off the extra water, which the original poster said he did.
 
First, I don't think your bazooka screen is ideal for fly sparging. If you're going to fly sparge, you may want to consider a false bottom.

Secondly, instead of checking your gravity of the runnings when you reach your preboil volume, why not check the preboil gravity in total? If you're where you need to be then you are finished. I'd be happy to give up 2% to save boiling an extra 30 minutes, so check your preboil volume and see where you're at.
 
azeeb said:
No that is not correct. If you sparge longer you get more sugar in your kettle and your final post boil gravity will be higher. Assuming you boil longer to boil off the extra water, which the original poster said he did.
Click to expand...

If you are pulling low gravity wort, then you are adding some more sugar but your overall gravity will come down because you are adding volume. Think about it. Your first rubbings are really high, hense your total gravity at that time. As you sparge your gravity of runnings fall and so does your total wort OG.
 
Yes, but the original poster said he boiled the extra volume off. After the boil, there was no extra volume, only the extra sugar.
 
Yooper said:
First, I don't think your bazooka screen is ideal for fly sparging. If you're going to fly sparge, you may want to consider a false bottom.

Secondly, instead of checking your gravity of the runnings when you reach your preboil volume, why not check the preboil gravity in total? If you're where you need to be then you are finished. I'd be happy to give up 2% to save boiling an extra 30 minutes, so check your preboil volume and see where you're at.
Click to expand...

I agree with this. Check the gravity of the total pre-boil wort, and stop when it gets to where it needs to be. The gravity of the runnings don't matter so much, as long as they stay above 1.010 or so.
 
Azeeb is correct. The more you sparge, the more total gravity points you'll pull out of the grain. Assuming you boil down to achieve target volume, sparging with more volume will ALWAYS result in more final gravity points (until of course you reach the theoretical yield of the grain - I stress that this is only theoretical) not less.

But, I think the problem is coming in the way of measuring effeciency. The OP states he achieved only 78% efficiency with this batch (which by the way, is nothing to be upset about. Planning on routinely hitting above that, while attainable, is not the norm for most home brewers). BUT, none of us knows how he calculated efficiency. Many brewers (and I'll assume Celtic and WHYB fall into this catagory) measure efficiency pre-boil. So, more sparge will decrease efficiency.

I find fault with that method because I want to measure my target finished product versus my actual finished product. This, I know, is not accepted by everybody and I'm not trying to debate the merits of one versus the other. As long as YOUR measurement of efficiency remains consistent, your adjustments will work.

By and large, what I truly want to know is how much of the actual potential gravity points from the grains ended up in my beer - with all factors included (loss, spillage, absorbtion, sparging, etc).

Regardless, I think this is the cause of the disagreement. I think the corrective action and suggestions are all on point. Just my .02.
 
cimirie said:
Azeeb is correct. The more you sparge, the more total gravity points you'll pull out of the grain. Assuming you boil down to achieve target volume, sparging with more volume will ALWAYS result in more final gravity points (until of course you reach the theoretical yield of the grain - I stress that this is only theoretical) not less.

But, I think the problem is coming in the way of measuring effeciency. The OP states he achieved only 78% efficiency with this batch (which by the way, is nothing to be upset about. Planning on routinely hitting above that, while attainable, is not the norm for most home brewers). BUT, none of us knows how he calculated efficiency. Many brewers (and I'll assume Celtic and WHYB fall into this catagory) measure efficiency pre-boil. So, more sparge will decrease efficiency.

I find fault with that method because I want to measure my target finished product versus my actual finished product. This, I know, is not accepted by everybody and I'm not trying to debate the merits of one versus the other. As long as YOUR measurement of efficiency remains consistent, your adjustments will work.

By and large, what I truly want to know is how much of the actual potential gravity points from the grains ended up in my beer - with all factors included (loss, spillage, absorbtion, sparging, etc).

Regardless, I think this is the cause of the disagreement. I think the corrective action and suggestions are all on point. Just my .02.
Click to expand...

You are correct sir; pre-boil efficiency. The ol' PBE. There now there is a new acronym to remember.
 
Celticway said:
If you stoped at 6.5 gallons like anticipated, you would have been even higher in the OG department. So you let the gravity of the run off drop to reduce the OG of the wort, which means you can use less grain to acheive your target next time.
Click to expand...

I see what you're saying.

I guess my next question is this: is there a way to get the same efficiency, without having to use an extra gallon of water and without having to do an hour and 45 minute boil to get my volume down to the proper volume?
 
Yooper said:
First, I don't think your bazooka screen is ideal for fly sparging. If you're going to fly sparge, you may want to consider a false bottom.

Secondly, instead of checking your gravity of the runnings when you reach your preboil volume, why not check the preboil gravity in total? If you're where you need to be then you are finished. I'd be happy to give up 2% to save boiling an extra 30 minutes, so check your preboil volume and see where you're at.
Click to expand...

My temperature corrected pre boil volume was .002 points higher than expected (after I had collected the 7.5 gallons and plugged it all into the computer.)

I didn't think to take one prior to running the final gallon through.

Re: speed of sparge, it was a 1 hour sparge for 6.5 gallons, so I'm guessing it might be an issue with channeling and the bazooka screen?

Thanks for the insight, it's slightly maddening to have issues with efficiency.
 
Rob, a few things that may be helpful here.

1. Know the maximum extract potenial of your grain bill. (this is something you can look up for each grain by maltser, though generally it's around 1.036-37)
ie. 1.036 X 10.5 lbs = 378 (gravity units) (this is the maximum you could hope to achieve)

2. Measure your total preboil gravity and X's that by your total volume to = YOUR gravity units. ie. 1.042 (preboil gravity) X 7.5 gal (preboil vol.) = 315 (gravity units achieved)

Some quick math 315div by 378 = .833 This will give you (in basic terms) the efficiency you are getting from your mash tun into your kettle. (83%)

3. Evaporation rate/ kettle loss. To know this simply, you should measure your (preboil)starting volume (-4% if taken @ boiling temps, compensate for expansion) and your final cooled volume in the fermentor. Measure for a 60 min interval.
So if you started with 6.5 gallon and achieved 5.5 into the fermentor (after 60m)...

Math here would be 6.5 gal div by 5.5 gal. = 84.6, Evap/kettle loss of 15.4%

Getting to know these numbers will help you dial in your setup, so you can better predict the results, lots of variables here though, so you will need to brew lots of beer to get it just right:)
 

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