OG is pretty far off, but all the numbers are right.

[jeremydgreat]

Wondering if you guys can help me with something. I brewed this recipe:

http://www.brewersfriend.com/homebrew/recipe/view/59350/hopstand-ipa-v2-citra-amarillo

... everything went perfect. I hit 86% efficiency, hit my mash temp to the degree, and had the correct starting and finishing volumes.

But in the end I measured my OG at 1.06 when it was supposed to be 1.072.

I wish I had more to say about this, but I'm really just baffled. Everything I did was as you see it in the recipe, but I somehow ended up way too low.

I've been doing this for a while and I haven't beed so wildly off since I first started brewing! Any thoughts?

 

[bigbeergeek]

How are you calculating your "efficiency" if your OG was 12 points low? What efficiency did your recipe predict?

 

[Demus]

+1. By definition if you are 12 points low you did not hit 86% efficiency. How did you measure 86%? I think that's where your issue lies..

 

[jeremydgreat]

How are you calculating your "efficiency" if your OG was 12 points low? What efficiency did your recipe predict?

I took a refractometer reading, converted it to an OG reading (using this) and then popped the OG and the recipe into this to get the brewhouse efficiency. Using that calculator, I've got over 80% before, although I think 86% is a record for me.

Wasn't expecting to see a post-boil OG lower than what the recipe predicted!

 

[bigbeergeek]

What was your pre-boil volume? Post-boil volume? You should have a handle on your boil losses; if you hit your pre-boil numbers and volumes than you shouldn't be this low. Did you simmer instead of your usual hard boil? Did you end up with excess wort? Was your refrac clean, calibrated and was the sample stirred/representative of the batch?

 

[jeremydgreat]

What was your pre-boil volume? Post-boil volume? You should have a handle on your boil losses; if you hit your pre-boil numbers and volumes than you shouldn't be this low. Did you simmer instead of your usual hard boil? Did you end up with excess wort? Was your refrac clean, calibrated and was the sample stirred/representative of the batch?

All the numbers are there in the recipe:

http://www.brewersfriend.com/homebrew/recipe/view/59350/hopstand-ipa-v2-citra-amarillo

The preboil volume was 7.5gal and after a 60 minute boil, cooldown, and filter, I ended up with 5.2gal in the fermentor. No excess wort or water top off. The refracto was definitely clean. I just checked it now using tap water, and it sits at 0.

Gah! This is driving me bonkers.

Using the cooled wort from my hydrometer reading, I just put a few drops in the refracto, and it also shows 1.06 OG. So odd.

 

[jeremydgreat]

I also just did an iodine color test on the post-boil wort (does that work after the boil?) I didn't see any color change (reaction to starch.)

 

[ajf]

All the numbers are there in the recipe:

http://www.brewersfriend.com/homebrew/recipe/view/59350/hopstand-ipa-v2-citra-amarillo

The preboil volume was 7.5gal and after a 60 minute boil, cooldown, and filter, I ended up with 5.2gal in the fermentor. No excess wort or water top off. The refracto was definitely clean. I just checked it now using tap water, and it sits at 0.

Gah! This is driving me bonkers.

Using the cooled wort from my hydrometer reading, I just put a few drops in the refracto, and it also shows 1.06 OG. So odd.

What was your Brix reading from the refractometer?
What was your wort correction factor? and how did you calculate it?
What was the temperature of the wort when you checked it with the hydrometer?
Have you ever calibrated your hydrometer by measuring the SG of distilled water at the specified calibration temperature for the hydrometer?

-a.

 

[Demus]

What was the pre boil gravity?

 

[jeremydgreat]

What was the pre boil gravity?

1.052

The recipe said I was supposed to be at 1.05

Any ideas? How could the OG be so far off after boiling, cooling, and then taking a reading right before pitching the yeast and letting it ferment?

 

[dyqik]

1.052

The recipe said I was supposed to be at 1.05

Any ideas? How could the OG be so far off after boiling, cooling, and then taking a reading right before pitching the yeast and letting it ferment?

How did you measure this, and how did you collect the sample?

 

[BackAlley]

Recipe calls for 12 lb of grain. I don't see that getting you to 1.072. I'd say 1.060 would be right on the mark with a 60 min boil. I think recipes not right. It calls for a 1.050 preboil. You'd have to boil the 7.5g down to 5.2 g which is way more then I'd expect for a 60 min boil

 

[jeremydgreat]

Recipe calls for 12 lb of grain. I don't see that getting you to 1.072. I'd say 1.060 would be right on the mark with a 60 min boil. I think recipes not right. It calls for a 1.050 preboil. You'd have to boil the 7.5g down to 5.2 g which is way more then I'd expect for a 60 min boil

hmm. So, maybe the recipe builder on brewersfriend.com is off then. That would be a shame. I can't imagine I'm the first person to discover a major bug like that!

Also, I boiled down to about 6 gallons. After cooling for about an hour and then leaving behind a half gallon of hops (there was a lot of hops in this recipe and I filtered them all out before adding the wort to the fermentor) I ended up with 5.2 gal.

 

[jeremydgreat]

How did you measure this, and how did you collect the sample?

I took the pre-boil wort gravity using a refractometer. The refractometer was calibrated today and when I took the OG reading (post boil) I double checked it with a standard hydrometer and it was right on.

So, unless refractometers are no good for pre-boil wort measurements, I can't see why it would be off.

 

[Bobby_M]

My guess: You took your preboil sample from a stratified wort. Typically when you fly sparge, your boil kettle collection doesn't necessarily get fully integrated until you reach boil. If you took your sample without stirring first, it could have been artificially high meaning it didn't represent the average gravity.

 

[larrybrewer]

This is Larry from Brewer's Friend. Came up with the following:

A) Gravity readings
I have a cheap refractometer off Amazon, and it reads all over the place. I need to take about 8 samples then average them to get anywhere near what my hydrometer tells me, and still it can be off. Refractomers are finicky tools that need to be calibrated pretty much before every use. I also have a $300 digital model and it reads much closer, but still I tend to trust my good old fashioned hydrometer over both these gadgets. Your boil gravity was higher than predicted, this tells us perhaps that reading was wrong in the other direction. It isn't clear if the readings were all temperature corrected, or if the kettle was stirred. Stratification is a potential culprit here too.

B) Not as much boil off
Sounds like you boiled off less than expected? That would factor into it.

This dilution calculator is handy: http://www.brewersfriend.com/dilution-and-boiloff-gravity-calculator/

In this case, the 'fermentor' mode was unaware of just how much losses you are giving over to hops absoroption and kettle dead space. This is something we want to add into the 'More...' section in the near future. We are currently implementing a feature that will allow for multiple equipment profiles, and this will be addressed soon after.

C) Definition of efficiency
Part of the issue is the definition of 'efficiency'. The recipe is set to batch size mode 'fermentor', this means efficiency is defined as 'brew house efficiency'. Sounds like you have 86% BHE dialed in from prior batches, but it is not clear if we agree on terminology. To clear that up, please see our FAQ on efficiency:
http://www.brewersfriend.com/faq/#recipes16

And see or FAQ on how we define 4 types of efficiency:
http://www.brewersfriend.com/faq/#recipes18


Next time:
To avoid variations in kettle dead space and hops absorption, try setting your recipe batch size mode to 'kettle', enter 86% kettle efficiency (or whatever your to the kettle efficiency is, usually ~5% higher than BHE) and pad the batch size up by your kettle dead space loss and hops absorption to get the correct amount in the fermentor at the end of the day. The water requirements section will help with that.

 

[larrybrewer]

Also, I boiled down to about 6 gallons. After cooling for about an hour and then leaving behind a half gallon of hops (there was a lot of hops in this recipe and I filtered them all out before adding the wort to the fermentor) I ended up with 5.2 gal.

This may also be part of it - the brew was not boiled down as much, and there was extra trub losses.

For all grain batches that have lots of kettle dead space and hops absorption batch size mode 'kettle' is much more appropriate.

 

[BackAlley]

The 12 lb of grain had 438 potential gravity points. Hitting 1.060 OG with 7.5g is 82%. Maybe you can eke out a little more but getting to 1.072??? Trub losses don't change OG, it only affects how much beer you're going to get.

 

[larrybrewer]

The 12 lb of grain had 438 potential gravity points. Hitting 1.060 OG with 7.5g is 82%. Maybe you can eke out a little more but getting to 1.072??? Trub losses don't change OG, it only affects how much beer you're going to get.

I believe he hit 1.060 with 6 gallons. 1.052 with 7.5 gallons.

 

[Glynn]

When i put your numbers in i get
preboil @ 1.050 for 7.5 gal
mash eff 86%
og of 1.058 @ 5.5 gal
with a total brewhouse eff of 74%
so by my system your dead nuts on

 

[dgr]

52*7.5/6.5 = 60 or an OG of 1.060. If you started with 7.5 gallons, you had 6.5 at the end of your boil. Either you measured starting gravity wrong or your estimate of what was left in the pot is off.
52*7.5/5.4 = 72 or an OG of 1.072. Easier to understand post boil volume = starting gravity * starting gallons / finished gravity. You would have needed to boil off 2.1 gallons to hit 1.072. That would have left 5.4 gallons IN YOUR KETTLE at the end of the boil.

 

[BackAlley]

I believe he hit 1.060 with 6 gallons. 1.052 with 7.5 gallons.

Yup, that's what I meant to type and what I used to come up with the 82%

 

[Glynn]

Your brewhouse eff is set to high. shoot for 75% Is it possible your confusing mash eff with brewhouse eff?

 

[jeremydgreat]

My guess: You took your preboil sample from a stratified wort. Typically when you fly sparge, your boil kettle collection doesn't necessarily get fully integrated until you reach boil. If you took your sample without stirring first, it could have been artificially high meaning it didn't represent the average gravity.

Great thought. However, I distinctly remember giving the wort a stir before dipping my spoon in and getting a couple drops. That doesn't mean it wasn't totally unstratified though.

So far, I think this is the most likely culprit.

 

[jeremydgreat]

I believe he hit 1.060 with 6 gallons. 1.052 with 7.5 gallons.

Correct. 1.072 was what the recipe builder predicted.

 

[jeremydgreat]

Your brewhouse eff is set to high. shoot for 75% Is it possible your confusing mash eff with brewhouse eff?

The brewhouse efficiency was set to 75%. I after gathering a pre-boil gravity reading on 7.5 gallons, the calculator gave me my brewhouse efficiency.

I adjusted the recipe to read 86% BHE to reflect what actually happened. And with a BHE of 86%, it says I should have been at 1.072 OG, when in fact I was at 1.06 OG.

 

[jeremydgreat]

Your brewhouse eff is set to high. shoot for 75% Is it possible your confusing mash eff with brewhouse eff?

You know what...

that's it.


Holy jeebus. I didn't know "brewhouse" and "mash" efficiency were 2 different things.

After I pop my recipe into the calculator and put in my gravity reading I took from the fermentor (which was 1.06... just before pitching the yeast), the results show that I'm at 71% BHE.

If I pop 71% into the recipe editor, I get 1.06. Which is exactly what I my OG was.

 

[dieden187]

I'm really glad you had that mix-up and were willing to lay it out there. I could foresee me doing the same exact thing in the next couple months after I got a brewing software. I'm OCD with checking numbers, but not so OCD about knowing that I use the same definition for words and processes as everyone else.