tough problem: getting correct pre-boil volume & SG with scaled recipe

[philipCT]

How can I scale a recipe to the efficiency of my setup, and achieve the volumes I'm looking for, without adding any mash runnings less than 1.008 in gravity, all without overshooting the wort OG.

It's a classic three parameter optimization and I don't know how to fix it.

Here's what's going on:

Using established BeerSmith process, I scaled a recipe (see below) based on 70% efficiency to 80%, which is what I'm currently using while I'm still dialing in my brewery (I'm six batches in). This predicts 86% mash efficiency using BeerSmith.

While drawing off wort from the mash and fly sparging per Kal's practices, I measured runnings periodically and stopped when gravity got to 1.008 to avoid heavy tannins. At that point, I only had 9.5 gallons, not the 12.85 gallons pre-boil I was looking for.

So this was disappointing, but then I measured the gravity of the BK and came out with 1.040 on the pre-boil wort, instead of the 1.034 predicted. So although I had to stop collecting at 3+ gallons short of what I needed, the gravity was way high. In fact, using BrewersFriend wort dilution calculator, I added 1.5 gallons of left over sparge water to achieve a little over 11g. Not what I was looking for, but better.

I also noted that post-boil OG was 1.040 - right on target after all that messing around. So I probably saved the brew just fine - I'm not worried about that because it's in the fermenter and there's nothing more to be done about it. But I really need an answer to the question posed in the first sentence above to brew other recipes in the future.

Any thoughts, experiences?

--Brew Notes--

Original Recipe for 10g @ 70% efficiency (omitting hops for brevity):

Biermuncher's Centennial Ale:

****10-Gallon Batch****
Batch Size: 11.00 gal
Estimated OG: 1.039 SG
Brewhouse Efficiency: 70.0 %
Boil Time: 60 Minutes

Ingredients:
------------
14.00 lb Pale Malt (2 Row) US (2.0 SRM) (80%)
1.25 lb Cara-Pils/Dextrine (2.0 SRM) (8.6%)
1.00 lb Caramel/Crystal Malt - 10L (10.0 SRM) (5.7%)
1.00 lb Vienna Malt (3.5 SRM) (5.7%)
​

-------------------------------------------------

Recipe scaled using Beersmith for 80% efficiency/86% mash efficiency:

Batch Size: 10.40 gal
Brewhouse Efficiency: 80.0 %

Ingredients:
------------
11.18 lb Pale Malt (2 Row) US (2.0 SRM) (77.1%)
1.21 lb Cara-Pils/Dextrine (2.0 SRM) (9.1%)
1.19 lb Caramel/Crystal Malt - 10L (10.0 SRM) (8.2%)
0.80 lb Vienna Malt (3.5 SRM) (5.5%)
​

 

[tdbc2011]

This may not be an answer to your question, but I hope it helps. I do not use Beersmith, but I do take several gravity readings during the sparge. I collect 7 gallons for a 60 minute boil and 7.5 gallons fir a 90 minute boil. I will take the last gravity reading with about a quart to go in my final volume (7.25 for a 7.5 collection). NOW with all that said, I have found that if I am down to around 1.010 to 1.008 then I have great efficiency. Usually around 85%.

 

[philipCT]

This may not be an answer to your question, but I hope it helps. I do not use Beersmith, but I do take several gravity readings during the sparge. I collect 7 gallons for a 60 minute boil and 7.5 gallons fir a 90 minute boil. I will take the last gravity reading with about a quart to go in my final volume (7.25 for a 7.5 collection). NOW with all that said, I have found that if I am down to around 1.010 to 1.008 then I have great efficiency. Usually around 85%.

So are you concerned about tannins when your runnings hit gravities lower than 1.008?

 

[acidrain]

Using established BeerSmith process, I scaled a recipe (see below) based on 70% efficiency to 80%, which is what I'm currently using while I'm still dialing in my brewery (I'm six batches in). This predicts 86% mash efficiency using BeerSmith.

I'm not understanding this. You started with a 70% efficient recipe, scaled it to 80% in beersmith, and then beersmith predicts 86%? Huh?

If Beersmith now says you will get 86%, but your equipment efficiency is predicted at 80%, you will be short on runnings.

Do you have your equipment profile accurately entered including boil off in amount and not percent?

 

[Kingbogart]

I'm with acidrain. Something is off. Based on the information you've provided it sounds like you didn't get the efficiency you were expecting, you hit low in the end, not high. You were wanting to have 437 points, but came out with 380. Your solution in this case is more grain.

 

[acidrain]

If you are really close to hitting your gravity, and your only worry is low SG sparge, you could start with a little thinner mash, and collect less to get your pre-boil volume.

 

[Mike_kever_kombi]

While I have admittedly never read Kal's writings for sparging, I am confused by the whole tannin extraction below 1.008. Why does he think this would be so?

Tannin extraction has more to do with PH than it does with some arbitrary number.

If you are worried about PH, below a certain threshold, have you considered treating your sparge water to lower the PH?

 

[acidrain]

I think I see the beersmith folly... BS always shows brewhouse efficiency. Forget this. Always calculate mash efficiency.
Like Kingbogart said... you may have to bump up your grain bill.

 

[Kingbogart]

Tannin extraction has more to do with PH than it does with some arbitrary number.

I believe this is correct. If I remember correctly (maybe not) as the sugars are washed away the buffering capabilities of the water drop significantly. After around 1.010 and below the pH will begin to rise drastically faster as a result. Basically the low sugars become an indicator for what the pH is about to do.

 

[acidrain]

While I have admittedly never read Kal's writings for sparging, I am confused by the whole tannin extraction below 1.008. Why does he think this would be so?

Tannin extraction has more to do with PH than it does with some arbitrary number.

If you are worried about PH, below a certain threshold, have you considered treating your sparge water to lower the PH?

Because a thinner mash has less buffering effect from the grains. As gravity lowers, PH goes up. It's a fact.

 

[tdbc2011]

So are you concerned about tannins when your runnings hit gravities lower than 1.008?

I have only gotten to 1.008 a couple of times and just quit with the sparge at that time. If I am a quart or so short then I really don't worry to much. I usually have about some beer left in the conical when I keg.

 

[philipCT]

I'm not understanding this. You started with a 70% efficient recipe, scaled it to 80% in beersmith, and then beersmith predicts 86%? Huh?

If Beersmith now says you will get 86%, but your equipment efficiency is predicted at 80%, you will be short on runnings.

Do you have your equipment profile accurately entered including boil off in amount and not percent?

Yeah, sorry, I should have simplified that. In BeerSmith, you can only enter a single figure labelled "Tot Efficiency". Having done that, BS calculates your "Est Mash Efficiency". Mine is 86%.

At the moment, I don't care about anything but mash efficiency/yield, so boil-off rates are moot (but they are, in fact correct).

I guess I'm getting great mash efficiency, in fact it appears I'm getting all the predicted starch & sugars out of the grain long before I've collected the desired amount of wort to the BK. This is based on my 9.5 gallons collected being at such a high gravity that I was able to dilute with water to get back down to the target pre-boil gravity.

So the solution does not appear to be to add more grain. If I did that I'd just be overshooting the OG, and that is exactly the problem I'm trying to solve. The first three brews on this system I got crazy high ABVs. While that's not the worst thing in the world I do want to be able hit the OG per recipe (plus or minus a little, of course - I'm not fussy).

 

[Kingbogart]

Total points. You wanted to have 12.85 gallons of 1.034. That's 437. You collected 9.5 gallons of 1.040. That's 380. Obviously that isn't enough.

So, either you aren't getting the 85% efficiency you were shooting for which you are adamant isn't the case. Or you need to add more grain to make up the rest of the sugars. If you got all the sugar out of all the grains, then the answer is to add more grain. You're short about 57 points, or about two pounds of base grain.

 

[philipCT]

I'm with acidrain. Something is off. Based on the information you've provided it sounds like you didn't get the efficiency you were expecting, you hit low in the end, not high. You were wanting to have 437 points, but came out with 380. Your solution in this case is more grain.

You could be partially right, but remember, my 9.5 gallons of wort hit 1.040, where the predicted pre-boil volume & gravity was 12.85g/1.034.

Using BrewersFriend wort dilution calculator, I added 1.68 gallons of water to achieve 1.034, totaling 11.18 gallons of wort. So at that point, I had the target gravity, but still missed the target vol by a bit more than 1.5 gallons.

I could have diluted with another 1.5 gallons to get to 12.85 and only missed SG by 4 pts (1.030).

So I could definitely add more grain, but it doesn't seem like that will solve the entire problem.

What to think about next?

• change mash thickness
• sparge faster
• add more grain
• make a standard practice in cases like this of just adding sufficient top-off water to fermenter to achieve target fermenter vol