Missed my OG by 10! Any idea what went wrong?

[philly224]

So I did a five gallon BIAB today and missed my OG by 10. I used 12lbs of 2-row and a lb of crystal 40l. My reading was 1.040 after a 75 min mash with 8 gallons of starting water. Is that low?

After that did the boil starting with about 7.5 gallons and ended with 6 gallons, half a gallon over my target. My OG was 1.050.

Was my screw up bad efficiently in the mash, too much water after the boil, or both?

My target OG was 1.060

I ordered a grain mill so hopefully that'll help a bit.

 

[doug293cz]

So I did a five gallon BIAB today and missed my OG by 10. I used 12lbs of 2-row and a lb of crystal 40l. My reading was 1.040 after a 75 min mash with 8 gallons of starting water. Is that low?

After that did the boil starting with about 7.5 gallons and ended with 6 gallons, half a gallon over my target. My OG was 1.050.

Was my screw up bad efficiently in the mash, too much water after the boil, or both?

My target OG was 1.060

I ordered a grain mill so hopefully that'll help a bit.

Need to know how much water you started with (strike volume.)

Brew on

 

[philly224]

Need to know how much water you started with (strike volume.)

Brew on

8 gallons

 

[Silver_Is_Money]

Brewhouse efficiency seems to be in the general neighborhood of about 67%. That's roughly what I generally get also. What ballpark brewhouse efficiency do you normally see? What would you like to see?

If you had boiled away that extra half gallon, you would have ended up at ~1.055.

 

[philly224]

Brewhouse efficiency seems to be in the general neighborhood of about 67%. That's roughly what I generally get also. What ballpark brewhouse efficiency do you normally see? What would you like to see?

The recipe I used was expected efficiency of 70 so right around that. So maybe the issue is I didn't boil enough water off?

 

[h22lude]

Why did you start with 8 gallons? Did the recipe tell you to, did you guesstimate or did you use software with your system as a profile?

 

[Norselord]

This is why i always recommend measuring your post mash gravity.
It gives you the opportunity to boil a little longer to raise your gravity.

 

[philly224]

Why did you start with 8 gallons? Did the recipe tell you to, did you guesstimate or did you use software with your system as a profile?

Because I keep missing my 5.5 gallon target with about 7-7.5 gallons and thought that would be good. Next time I'm going to go for 7.5 again...

 

[doug293cz]

Sorry, I missed that you had your strike volume in your OP.

Anyway, plugging your numbers into a mash/sparge simulator indicates that your conversion efficiency was around 76%. This is extremely low. You should be able to achieve conversion efficiencies of 95% or better, if you have a good crush and your mash pH is in the range of 5.2 to 5.7. Your lauter efficiency was about 85%, which is very good, but because of the low conversion efficiency your mash efficiency was only about 65%.

A finer crush should improve your conversion efficiency, and thus your mash efficiency (since mash efficiency equals conversion efficiency times lauter efficiency.)

Brew on

 

[philly224]

Thanks! It seems like I had multiple issues going on here. I'm going to try and brew again with the same grain bill when I get my mill and knock the water down half a gallon and try a finer crush.

What calculator did you use to get all that info?

 

[h22lude]

Because I keep missing my 5.5 gallon target with about 7-7.5 gallons and thought that would be good. Next time I'm going to go for 7.5 again...

This is your problem. You can't just guess and hope it comes out right. Most of the time it won't. You need to take good volume and gravity notes and use a calculator like BeerSmith.

Do you know your boil off?

 

[doug293cz]

Thanks! It seems like I had multiple issues going on here. I'm going to try and brew again with the same grain bill when I get my mill and knock the water down half a gallon and try a finer crush.

What calculator did you use to get all that info?

It's a mash/sparge simulator that I wrote based on work done by Kai Troester. I haven't cleaned it up enough to make it publicly available yet. You can get similar results by playing around with @pricelessbrewing 's "BIAB" on-line calculator (I helped with the math used by that website.) The calculations have been validated by looking many sets of brew session data.

Brew on

 

[philly224]

This is your problem. You can't just guess and hope it comes out right. Most of the time it won't. You need to take good volume and gravity notes and use a calculator like BeerSmith.

Do you know your boil off?

No I don't unfortunately. I'll figure out how to find that out for next time.

 

[doug293cz]

No I don't unfortunately. I'll figure out how to find that out for next time.

I had your total boil off figured at 1.36 - 1.37 gal after adjusting your pre-boil volume for temperature expansion. This seems a little high. You might want to think about reducing the heat during boil.

Brew on

 

[philly224]

Thanks!!

 

[h22lude]

No I don't unfortunately. I'll figure out how to find that out for next time.

Boil a couple gallons of water for an hour and see how much you have left. The difference is your boil off. Very important. I think you just need to use something like BeerSmith. There are others but I find this to be the best (of course that is just my opinion).

I had your total boil off figured at 1.36 - 1.37 gal after adjusting your pre-boil volume for temperature expansion. This seems a little high. You might want to think about reducing the heat during boil.

Brew on

My boil off is 1.8 gallons. Not sure why it is so high but there is nothing I can do about it. I've turned my element down as much as possible to keep a moving boil and still that high. I just think some people have high boil off depending on kettle dimensions, humidity, ambient temp, etc.

 

[philly224]

Trying to set up my equipment profile in Brewers friend now. It has the grain absorption at .5 qt per lb. That seems way too high right?

 

[h22lude]

Trying to set up my equipment profile in Brewers friend now. It has the grain absorption at .5 qt per lb. That seems way too high right?

I believe that is a typical average but it also depends on if you squeeze the bag or not.