Incredibly Frustrated With Poor Efficiency

[brumasterj]

Sure seems like a lot of water to me for a small grain bill, post boil 6.5 gal???
Maybe reduce your pre boil and post boil shoot for 5.5 gal?
Another thing you could do is mash with half the water and have the other half heating to 170 pour over grains at end of mash to rinse! It wasn’t uncommon for me to hit 80-85% doing it this way back in the day

 

[VikeMan]

So, it is really the limit dextrinase that is responsible for the higher fermentability of lower temp mashed wort, not beta amylase.

I sometimes wonder why people tend to ignore Limit Dextrinase, and my speculation always comes around to Palmer's "How to Brew," i.e. the original (now online) edition that mentions it only in passing (in a table of mash enzymes), without actually naming it. It says "Debranching (var.)" and lists the function as "Solubilization of starches." Thus a lot of folks' introduction to Limit Dextrinase was dubious at best.

In Palmer's defense though, I think when the first edition was written, studies investigating the impact of Limit Dextrinase under mash conditions were just beginning to appear, whereas the prevailing conventional wisdom was that mash temps denatured it too quickly.

 

[1galbrewer]

I struggled with efficiency for a long time and think I found the checklist that gets me to a good efficiency.

• Although I think you already have this locked down, make sure you add your salts and acid before the mash.
• Stir a few times throughout the mash.
• Mash with your full volume of brew water, or close to it. I leave a tiny bit out to do a pseudo-sparge. Using my full volume boil water was my main problem (I pour hot water from a tea kettle over the lifted grain bag)
• ***Use a mash out temperature! This was big for me as well. The stated reason I see for this is that raising the temperature to around 168F increases the solubility of sugars in water, relative to your main mashout temperature.
• Figure out your post-boil volume by putting your wort chiller in your brew kettle, filling the kettle up to your batch volume, and marking that water level somehow.
  • I use a ruler. Near the end of the boil, I just pour a little boiling water into my brew kettle if the level is a little low. I also brew an extra little bit more to account for trub losses.

This is just what worked for me. Hope it helps.

 

[Monmouth00]

I put your numbers into the Brewer's friend Brewhouse efficiency calculator and it shows 79.83 % efficiency. Isn't that good enough?
Am I looking at the numbers wrong?
The Boil volume was 8.0 gallons and the Post boil was 6.47 of 5% ABV beer. If you re-brew and use one gallon less water, you will end up with a higher ABV since you will have only 5.5 gallons of beer at the end.
This seems like a pretty simple solution to the OP's problem to me; Am I right or wrong on this?

And herein lies some of my frustration - I put those numbers into Beersmith and get 62.5% efficiency.
Again, I may not be using Beersmith correctly.
If it is indeed 79.83% efficiency, it's more than enough for me. I want to target 75% as a minimum.
I'm already planning on using less water to brew the next batch. I've been confused about the strike water volumes since the beginning, so this will be one of my next adjustments.

 

[Monmouth00]

I struggled with efficiency for a long time and think I found the checklist that gets me to a good efficiency.

• Although I think you already have this locked down, make sure you add your salts and acid before the mash.
• Stir a few times throughout the mash.
• Mash with your full volume of brew water, or close to it. I leave a tiny bit out to do a pseudo-sparge. Using my full volume boil water was my main problem (I pour hot water from a tea kettle over the lifted grain bag)
• ***Use a mash out temperature! This was big for me as well. The stated reason I see for this is that raising the temperature to around 168F increases the solubility of sugars in water, relative to your main mashout temperature.
• Figure out your post-boil volume by putting your wort chiller in your brew kettle, filling the kettle up to your batch volume, and marking that water level somehow.
  • I use a ruler. Near the end of the boil, I just pour a little boiling water into my brew kettle if the level is a little low. I also brew an extra little bit more to account for trub losses.

This is just what worked for me. Hope it helps.

• Yes, my water is built and thoroughly mixed before I mash.
• Yes, I stir at least two times, then I circulate with a pump for a few minutes after the mash to dump any escaped particles back on top of the grain bed.
• I haven't sparged, and probably won't. I brew in my garage and I don't have a water source in there or anywhere to heat it.
• Yes, I mash out at 168-170 for about 10 minutes before I pull the bag and squeeze like hell.
• I use this and a ruler to closely estimate the volumes: https://manskirtbrewing.com/Calculators.aspx

I really appreciate the advice. Fingers crossed I get my volumes more accurate for the next batch. I think I have a better way to estimate now.

Cheers!

 

[pers]

Sorry if I missed this but didn't see it mentioned after quick glance.

What batch size are you aiming for?

If its the traditional 5-5.25 gallon batch it looks like you're using too much water for mashing. My full volume biab mash for a 5.25 gallon batch with an approximate grain bill that size would be a little over 7 gallons. You have 8.05 gal at boil, which means you started well over that.

Yeast attenuation seems normal. Think your lost gravity could just be too much initial water.

 

[IslandLizard]

I think it’s right at about 3 gallons under the false bottom.

I didn't recirculate during the mash this time - not until the very end at least.

That, ^ together with 3 gallons of water/wort of deadspace (underneath the false bottom) is counterproductive.
Either a) recirculate during the whole mash time, slowly, and prevent channeling, or b) eliminate the deadspace, so your mash can use the full volume.

IOW, I'd say your mash is way too dry currently. Those 3 gallons in the deadspace aren't working squat for your mash.

 

[ChiknNutz]

Just adding a bit more for comparison sake. I perform full volume BIAB mash with no sparging or vorlauf, simply a bag squeezer The last beer I made was a traditional Hefeweizen using 11# of grain and 1 oz. of hops. For my setup, I used 8.52G of strike water. I hit all my anticipated numbers, even slightly better. I recently obtained a new kettle and propane burner so am still dialing those in but tend to see about 1.33G of boil off for a 60-minute boil. I've found it really matters how strong your boil is. My last batch I boiled off way too much as I had the burner going to high.

SG: 1.044 (target was 1.041)
Pre-boil volume: 7.55 (target 7.51)
Post-boil volume: 6.05 (target 6.03)
Post-boil OG: 1.052 (target 1.051)

I do not use Brewhouse Efficiency but focus on the others (Conversion, Pre-Boil or Ending Kettle). When talking about efficiencies, you need to know which of these 4 is your target. TBH, I don't know what the most common one is to reference but I have found the overall Brewhouse Efficiency to be misleading since it accounts for ALL losses in the entire system. I care more about if I hit my mash efficiency than how much I lost from the kettle to the fermenter and such.

 

[AugustWest]

I agree with Tracer Bullet. If you want to get more out of BIAB, you'll want to mash with 1.2 - 1.5 qts per pound of grain, and soak/sparge in a separate vessel.

I think I am going to try this next time I brew and see if I can eek some more points out of those grains. Curious how others do this as relates to water chemistry. Do you just add all your salts in your mash to get to the right numbers and then use "plain" water for the sparge or do you treat both? I use Brewer's Friend and I know they have calculators for where the salt additions happen but until now I have only done full volume BIAB so I haven't had to go down that road.

 

[Monmouth00]

That, ^ together with 3 gallons of water/wort of deadspace (underneath the false bottom) is counterproductive.
Either a) recirculate during the whole mash time, slowly, and prevent channeling, or b) eliminate the deadspace, so your mash can use the full volume.

IOW, I'd say your mash is way too dry currently. Those 3 gallons in the deadspace aren't working squat for your mash.

I'm going to have to look again, but yeah, if I remember correctly, the false bottom screen is just barely covered by the water at 3 gallons. I have a large 15 gallon pot, 16" diameter. Approx. 3.5" of water is 3 gallons.

I'll go back to recirculating during the whole mash and seeing if this helps with my efficiency.

But, it brings me back to my problem of losing heat through the pump and tubing. I have to shorten the hoses, and perhaps up my temps to even out the grain bed temps. Currently a 152 degree setting on the Inkbird (thermowell below false bottom) gives me only 149-150 degrees when it gets back to the recirculation port on the lid.

Thanks for this perspective.

 

[tracer bullet]

I think your heat loss in the pump and tubing is fine. If a 152 setting gives you 149 - 150 that's A-OK. Kinda just how it goes, nothing to worry about, wouldn't call it a problem exactly. Just know that difference that happens for your setup, keep it in mind, and roll with it.

As for the 3 gallons, if it's that big of a pot then yeah it'll go fast and makes sense. I suppose I had more like a 10.5 gallon Anvil or similar in mind, where it's just under a gallon of dead space.

 

[Monmouth00]

So here's the plan for the next brew day:

• Start with closer to 7.5 Gallons of strike water
• Shorten hoses a bit
• Recirculate through entire mash, with some occasional stirring
• extend mash by 15-30 minutes
• Mash out slowly to 170 before pulling the bag
• Squeeze like hell

If that doesn't get me close to 80% you guys can have my equipment and I'm going back to extract.

Thanks for all the help - sincerely!!

Cheers!

 

[1galbrewer]

• Yes, my water is built and thoroughly mixed before I mash.
• Yes, I stir at least two times, then I circulate with a pump for a few minutes after the mash to dump any escaped particles back on top of the grain bed.
• I haven't sparged, and probably won't. I brew in my garage and I don't have a water source in there or anywhere to heat it.
• Yes, I mash out at 168-170 for about 10 minutes before I pull the bag and squeeze like hell.
• I use this and a ruler to closely estimate the volumes: https://manskirtbrewing.com/Calculators.aspx

I really appreciate the advice. Fingers crossed I get my volumes more accurate for the next batch. I think I have a better way to estimate now.

Cheers!

Damn, I have no clue what's causing that. I know how frustrating this problem can be. Goodluck! ...unless you were serious about giving away that equipment, in which case...I hope you fail

One last remark: Although I'm sure you've tried or considered it, maybe try a different base malt or try a different supplier? I'd say check if your recipe calculator has any errors in the ppg for your base malt, but I really doubt there's a mismatch there.

 

[BrewChatter]

I think I am going to try this next time I brew and see if I can eek some more points out of those grains. Curious how others do this as relates to water chemistry. Do you just add all your salts in your mash to get to the right numbers and then use "plain" water for the sparge or do you treat both? I use Brewer's Friend and I know they have calculators for where the salt additions happen but until now I have only done full volume BIAB so I haven't had to go down that road.

We've had a lot of luck with this method, and I usually just treat the mash water to ensure pH is on point and the enzyme is happy and 'sparge' (lol, usually my BIAB sparge consists of moving the bag to another pot with the calculated sparge volume at ~168 F and submerging it and moving it around for a bit) with my original water, usually RO/Distilled if I'm building a specific profile.

 

[DuncB]

Insulate those tubes with some pipe insulation, it's cheap and also protects you from burning, then you might not need to lose length!! Use a kettle or two of water for that pseudo sparge as mentioned above.

 

[sibelman]

OP is understandably interested in fixing an apparent efficiency problem. Some have suggested OP's "problem" could well be a mirage due to measurement error, software wackiness, incorrect assumptions/expectations. But the worry is real. I can relate: I like that my efficiency seems OK.

Much wisdom has been shared, notably the fine expositions on efficiency (conversion, lauter, brewhouse...), temperature, time, and enzymes by @doug293cz. This has improved my own understanding, and may well help the OP too. I'm grateful for the information and ideas I find here.

Chasing particular numbers offers its own reward but, at the risk of introducing RDWHAHB into a fruitful technical discussion: As others have stated, achieving higher efficiency (thus saving some grain bill money, and feeling good about one's process) ought to justify the effort and expenditure. Some suggestions for boosting efficiency are easy and cheap. Some will affect (adversely?) the resulting beer. I hope @Monmount00 embraces changes that feel like real improvements such as smoother process, lower cost, greater sense of mastery, and -- especially -- better beer.

Cheers. Oh, and while considering improvement, have a delicious homebrew (whether you "hit your numbers" or not!)

 

[AZ Maverick]

I have only just started all grain doing BIAB.
I use a 10 gallon kettle with no false bottom and no recirculation, I use a two layer Reflectix wrap for insulation around the kettle during the mash.
My last batch was a 9.36lb grain bill, I crushed my own grain with a two roller Hullwrecker set to .028" and a single pass crush.
I used 7.1 gallons of strike water and adjusted the ph of the mash with lactic acid to a measured 5.36 after adding the grain.
I did a 90 minute full volume mash and then squeezed the heck out of the bag, no mash-out or sparge, just a good stir three times during the mash.
My measured mash conversion was 94.1%, my final brewhouse efficiency came out to 77.5%.

 

[DuncB]

Nowt wrong with that.

 

[CascadesBrewer]

So here's the plan for the next brew day:

I am not sure what your system is like exactly. I am guessing the false bottom is there above some electric heating coils?? If not, the easiest solution is to remove the false bottom, turn off the pumps, crush finer, and (optionally) wrap up your kettle during the mash.

It seems like it is often the more complex systems that often struggle with efficiency. This is the BIAB forum after all, and a core of BIAB is simplicity. I know when I moved to BIAB I was skeptical. These days I just tune my setup to a 73% brewhouse efficiency with a full volume mash and minimal squeezing.

If the false bottom needs to be in place, is there a way to reduce the dead space? 3 gallons of dead space seems like a lot to try and work around.

 

[Jako]

i noticed you said estimated PH, have you tried taking a reading making sure its right? i had issues in the past with bad efficiency this was part of a few things i worked on.

 

[Julian Høstan Urrea]

I see many good answers here, but do you stir? I have to stir a couple of times during the mash. Also when sparing.

 

[bwible]

FWIW I use BeerTools recipe software. They have a free online version though its not as robust as the one you can buy. Its not terribly expensive. I’ve used it for 20 years, I find it easy to use, and I really like it.

You must be sure to mix your mash thoroughly. Dough balls or pockets of dry grain in the mash are the biggest efficiency killer. Grain that doesn’t get wet won’t give up its sugar.

I don’t BIAB, but I was always right around 69-70% efficiency with my cooler. Last year I sent my water to Ward for testing. After adjusting my water chemistry, which for me was as simple as adding a couple grams of gypsum to my mash water and an ounce or two of acidulated malt to my mash to bring ph in range - my efficiency went from around 70% to closer to 85%. I was pleasantly surprised. Those were the only changes I made.

 

[greenspan76]

I won’t rehash the suggestions you’ve already gotten, but I recommend you make a simple log to measure grain absorption, boil off rate, trub loss into fermenter, trub loss into keg/bottles, and of course gravity readings at each step using both refractometer and hydrometer. After doing 4-5 batches using the same equipment and process, create a new equipment profile and input the average of those calculated numbers into Beersmith for that equipment profile. (Don’t forget to enter you’re refractometer readings so it shows corrected numbers).

I had issues with Beersmith and wildly inconsistent brews until I did that and ever since I’ve been within 0.001 on my gravity readings every time.

 

[Bobby_M]

Boil off has very little effect on efficiency,

Just one nit pick here. Beersmith's efficiency is total brewhouse and in a BIAB no sparge, a half gallon higher boil off would use 1/2 gallon more strike water which would lower the post mash gravity. That means the absorption rate x gravity is essentially the "lautering" efficiency loss in that process. I guess it's a matter of semantics as to what "very little" effect means. It's definitely not going to make up 8% that the OP is looking for.

 

[Bobby_M]

You really don't have a problem in the grand scheme. If Beersmith is reporting that you have 62% brewhouse efficiency, that's what you feed back into your equipment profile so that the next time you brew you hit your exact ABV target. Chasing an efficiency number is a game for the production breweries where 1% efficiency = $700 in malt. You determine what your efficiency is and then you use that number to author or scale the next recipe to fit your system.

3 gallons of deadspace. Everyone chill out. You're getting ahead of yourselves. When a no sparge, full volume mash starts with 8-9 gallons of water, 3 gallons outside the bag is still 5-6 gallons INSIDE the bag. No the mash is not too dry. Yes, starch and enzymes will still diffuse through the bag and the wort at the bottom will still participate in the mash.

However, the recirculation will force that action to happen faster and you'll get faster conversion. The REAL reason to recirculate is to distribute that lower heat up into the top of the mash. Mashing at 149F for 60 minutes is really not enough for full conversion. When you do a batch with recirculation, you should only see about 1F difference across any area of the mash, colder near the kettle walls.

You can take gravity readings like every 10 minutes of mashing (collect the wort from the recirculation return line) and watch the gravity rise and then eventually plateau. When that happens, set the controller for 5 degrees hotter and see if the gravity doesn't rise again with the boosted temp. It's a good idea to record the gravity at the very end of the mash to see how much conversion or mash efficiency you achieved. That's basically the measure of the chemical process that occurred.

How much water to start with is not a matter of anyone's opinion. You have to record all your losses all the way through until kegging. If you fill your keg to the tippy top and there's still 1/2 gallon of perfectly clear beer in the fermenter you could have taken, you MAY reduce your fermenter loss setting by 1/2 gallon (I wouldn't because I like some buffer volume). You had a post boil volume of 6.5 gallons. That's what I usually target because I want 5.75 gallons in the fermenter and I build in that .75 gallons of trub loss in the kettle for that reason. People who dump every drop of wort into their fermenter, or people with 6 gallon fermenters with both tell you that 6.5 gallons is too much wort to end up with.

 

[Monmouth00]

People who dump every drop of wort into their fermenter, or people with 6 gallon fermenters with both tell you that 6.5 gallons is too much wort to end up with.

That's me. I use a hop spider and hop bags, so everything goes into the fermenter with very little trub. I just started doing this with my new setup, so my loss numbers were way off. I also know a bit more about how much I'm losing in the fermenter, as it's mainly just yeast and break materials settling out, as opposed to the hop particulate as well.

So, now that I know these numbers a bit better, I can do all I mentioned before, including lowering my strike water volume. I'm hoping it will result in a less diluted final product.

Thanks again, everyone. I do appreciate it. I'll revisit this thread after the next batch to update the progress.

Cheers!

 

[wepeeler]

I’m getting very different numbers in Beersmith, and am beginning to get very frustrated with it. I like it for building recipes, but there are so many inputs that dramatically alter the calculations. Again, I’m sure I’m not using it correctly and haven’t built my profile correctly, so it’s partially my fault.
I am likely going to switch over to using just Bru ‘n Water to build a base with distilled water, and relying exclusively on Brewer’s Friend for the rest. It’s the most comprehensive site I’ve found. I think I’m getting in trouble switching between the two softwares.
And, point noted with the hydrometer. I’ll start backing up measurements with that next time around. Switched to the refractometer to simplify, but the calculations seem like another spot for errors.

Setting an accurate equipment profile is an absolute must to accurately predict numbers. The program is only as smart as the information you give it. I had an awful time with "hitting numbers" when I first started using Beersmith, and it ended up being my own fault. Set up a few equipment profiles, depending on what style you're brewing. Obviously a NEIPA will differ from a Kolsch in the amount of hops you use, amount of grain therefore affecting the trub leftover (more hops, more grain to soak up water) etc. These little things all add up to helping predict a final outcome.

Others have mentioned crush, which is also a big factor. Most BIAB guys double crush. I do find it helps my efficiency as well.

What I would do if I were in your shoes, which I was a few years ago, is go back to your equipment profiles and make sure everything is entered as accurately as possible. If you want to PM me, I can help guide you through some screenshots and what not. I've since moved on to Brewer's Friend, which I like a lot better, but you still need accurate equipment profiles.

In the end, brewing the same recipe a few times in a row, or at least close to one another will help iron out any wrinkles in your system. Then switch to a different style and repeat. You'll get the hang of it, and there are plenty of people willing to help you get there!

 

[jdudek]

For what it's worth, I've given up on all the software out there when it comes to figuring out efficiency. I use brew father to build recipes and tracking brew day but I don't trust its numbers (it doesn't for example take grain moisture into account). I use doug293cz's spreadsheet with a few modifications to suit my needs and have never looked back. The whole idea of having to guess what your efficiency is going to be seems backwards to me. The difference in efficiency between your 4%ABV Irish stout and your 9% trippel is large. A predictive efficiency model like the above mentioned spreadsheet is miles better and I don't understand why the software out there does not adopt this model.

 

[VikeMan]

A predictive efficiency model like the above mentioned spreadsheet is miles better and I don't understand why the software out there does not adopt this model.

FWIW, BrewCipher has an integrated mash efficiency predictor, added in 2013.

 

[ScrewyBrewer]

I'll go back to recirculating during the whole mash and seeing if this helps with my efficiency.

Maybe it's me but I keep losing track of which efficiency you're referring to, mash, conversion, lauter, or brewhouse?

 

[bracconiere]

i'm going to chime in, again i think....and say sounds like there's a lot of people trying to cheat...funny coming from consistency is important crowd!

i just use beer smith's BH effec number, every time, so i can tell if i'm doing better or worse if it goes up or down.... the only reason i see to worry about 'different' effec'ies, is trying to bulls eye the problem, and i never could hit anything with a rifle...but i was pretty good at skeet...

 

[doug293cz]

For what it's worth, I've given up on all the software out there when it comes to figuring out efficiency. I use brew father to build recipes and tracking brew day but I don't trust its numbers (it doesn't for example take grain moisture into account). I use a doug293cz's sreadsheet with a few modifications to suit my needs and have never looked back. The whole idea of having to guess what your efficiency is going to be seems backwards to me. The difference in efficiency between your 4%ABV Irish stout and your 9% trippel is large. A predictive efficiency model like the above mentioned spreadsheet is miles better and I don't understand why the software out there does not adopt this model.

FWIW, BrewCipher has an integrated mash efficiency predictor, added in 2013.

@pricelessbrewing 's online calculator also contains a predictive mash/lauter efficiency model (I showed him how to do it.)

Brew on

 

[Julian Høstan Urrea]

i'm going to chime in, again i think....and say sounds like there's a lot of people trying to cheat...funny coming from consistency is important crowd!

i just use beer smith's BH effec number, every time, so i can tell if i'm doing better or worse if it goes up or down.... the only reason i see to worry about 'different' effec'ies, is trying to bulls eye the problem, and i never could hit anything with a rifle...but i was pretty good at skeet...

Only reason it matters to me is if I'm going to make that exact beer again. I normally hit my brewing softwares number.

 

[jerrylotto]

True dat. No beer is going to be perfect until you have made it at least a few times! And then who cares what the software says...

 

[jdudek]

@pricelessbrewing 's online calculator also contains a predictive mash/lauter efficiency model (I showed him how to do it.)

Brew on

sorry, indeed it does. I've used it a bunch as well over a period of time.

 

[Julian Høstan Urrea]

True dat. No beer is going to be perfect until you have made it at least a few times! And then who cares what the software says...

Exactly, but as you probably know. Its hard to make the same thing again . So many hop and malt combos to try, so little time

 

[RufusBrewer]

For me, the efficancy measurement that counts., the one that you need to be distracted by is the preboil. That is the one that tells you how well you converted your malt to sugar.

Using the recipe in the OP + the 9.4 brix = 1.038 and volume 8.05 gallons, passed through Brewers Friend, Efficiency = 75.7%.

Personally, I think homebrewers get wrapped around the axle over efficiency. The only reason to measure efficiency is so you can formulate recipes and get desired, predictable and consistent results. You can overcome getting 10% less effiicancy by using a pound or two more of malt. Not a biggie in my book.

 

[mhgodzilla]

Your numbers seem good to me if your getting 5% predicted abv. I’d double grind my grains at the LHBS. Also try a batch sparge with another 2 gallons just to be safe. How did the prior batches taste after the ferment?

I just did my first BIAB. Used Brewers Friend to calculate recipie, hops, volumes, gravity etc…Overshot the gravity a bit which was due to boiling off a more than expected and maybe better efficiency than I predicted . Got about 76-78% efficiency. Predicted 1.048 got 1.051+. Did the double grind. Did do a batch sparge.

 

[enkamania]

Ok, I calculate your mash efficiency as 74%. Your brewhouse efficiency will be lower than that by the ratio of Fermenter_Volume / Post-Boil_Volume.

I get your coversion efficiency as 83% - 84%, which is quite low. Conv eff should be 95% or higher. Biggest factors in conversion efficiency are crush and mash time.

Your lauter efficiency is about 89%, which is quite good. This high, no-sparge, lauter efficiency is the result of your very low grain absorption rate (0.041 gal/lb), which is achieved with aggressive squeezing.

Raising your conversion efficiency to 95% would bring your mash efficiency up to ~84%, and 100% conversion would bring your mash efficiency up to ~88%

Brew on

How do you calculate conversion efficiency?

 

[jdudek]

How do you calculate conversion efficiency?

max deg plato: (weight of dry grist * potential) / (weight of dry grist * potential + weight of strike water). X 100
conversion efficiency: measured deg plato/max deg plato X 100

weight of dry grist should take grain moisture under account typically, 4%. So if you have 10 pounds of base malt with an 80% yield, then the weight should be 10*0.96*0.8 = 7.68

weight of water is gallons * 8.3304 lbs/gallon.

use tables online to convert from plato and SG. Note brix and plato are not exactly the same.

OP has 11lbs of malt (To be precise we should check all the potential of the various malts and average, but it's mostly golden promise speced at 81%). 8.5 gallons of water.

Max plato: 11*0.96*0.81 / (11*0.96*0.81 + 8.5*8.3304) = 10.78 deg plato
measured plato: 9.4brix ~= 9.1 deg plato

conversion efficiency: 100 X 9.1/10.78 =~ 84%