Cant understand pre-boil gravity numbers

[jamorgan3777]

Okay, First time BIAB. Boiling right now but pre-boil gravity numbers are all whacked out.

9# 2-row
11oz Munich10
11oz Victory
8oz Malted wheat

Using BeerSmith. I put 8gal water in pot, heated to 163, ground grains (pretty fine) mashed in, temp settled out at 155F. Mashed for 75 min. Squeezed bag.

Ended with 7.25 gal. Measured gravity and it is 1.062!

BeerSmith was predicting 1.041 How am I that far off?

HELP!

 

[mux]

What temp was the sample? You need to correct for temperature. Most likely your hydrometer is calibrated for 60f.
this is what I use
http://www.brewheads.com/gravcorrect.php

 

[mux]

Actually beersmith has calculators, use them, and if it is still high use the dilution calculator to get where you need to be.

 

[jamorgan3777]

That is what is even stranger. High temp should read too low, not too high :confused

I think I can correct it by dilution, I am just wondering what in my process went wrong? Do I have BS set up wrong?

 

[calvin]

If your efficiency is set for non-BIAB, you might have just been that much more efficient, what with squeezing the bag and draining every last bit of sweet wort out of there. My efficiency was a good 10% higher when I tried BIAB. Granted, it was low to begin with, and I screwed up the temp controls completely, but the efficiency was there.

 

[mux]

Whats your hydrometer calibrated temp?

 

[jamorgan3777]

I just upped my hops to ~50 IBU and made it an American IPA

Guess I dont have trouble making "big" beers

 

[kable]

In Beersmith, what was the specified efficiency for the recipe? This is what the pre-boil computation is based on. Lower gravity beers like this give me about 85% efficiency without trying, using BIAB.

 

[phuff7129]

What do you have your efficiency set at in Beersmith?

 

[jamorgan3777]

You hit the nail on the head phuff! looks like I got better than 72% efficiency eh?

Thats totally it.

Thanks!

 

[phuff7129]

Glad I could help!

 

[robcj]

You hit the nail on the head phuff! looks like I got better than 72% efficiency eh?

Thats totally it.

Thanks!

Yup. 80% or higher is not unheard of when you crush the grains very fine for a BIAB. I usually get 80% with a mash out and no sparging or squeezing of the bag.

 

[jamorgan3777]

Yes. I have a lot of tweaking to do in beersmith I guess. I measured my OG after cooling and the boil and it was 1.060. How do I LOSE gravity by boiling? There must have been something wrong with my pre-boil sample or something.

 

[ajf]

There are two things that often cause inaccuracies measuring pre-boil volumes:

1. Temperature. Hydrometer temperature corrections are notoriously inaccurate at temperatures > about 90F. A properly calibrated refractometer can eliminate this problem, as will cooling the sample to < 90F
2. Mixing. The wort you collect after a mash is not homogenous. There will be high gravity layers and low gravity layers. A brisk stir of the collected wort for a minute or two before taking the sample will eliminate this problem.

-a.

 

[jamorgan3777]

Thanks! I never thought I about stratification that makes sense. Higher gravity material at the bottom. Thanks for the insight!