OG Issue

[DonT]

So I've had this issue crop up a few times now and I'm not sure why.
Whats happening is my post boil gravity is not what it's suppose to be. Mash goes fine, no issues, hit my number just fine. Sparge is fine, came within 3 points. Pre-boil gravity today was 1.051, was looking for 56... close enough. I have my boil off rate at 1g/hr. Boiled down just fine, ending with the correct amount. Now according to beersmith boil off tool, I should be at 1.061... nope.... 1.056. Why? I can't figure this one out... what am I missing here?
Yes I checked calibration on my refractometer this morning.
Thanks for any help!

 

[Sammy86]

Is your volume measurements accurate as well? Are you making sure your gravity readings are taken with a well mixed sample?

 

[DonT]

Is your volume measurements accurate as well? Are you making sure your gravity readings are taken with a well mixed sample?

Yes. I end up with what I'm shooting for, and I take multiple readings with different samples.

 

[day_trippr]

[...]Are you making sure your gravity readings are taken with a well mixed sample?

Right, "well mixed sample" is key...

Cheers!

 

[DonT]

Right, "well mixed sample" is key...

Cheers!

I took samples before and after transferring to fermenter. Same reading.

 

[tracer bullet]

Are you familiar with water expanding with heat?

6 gallons room temp is about 6-1/8 gallons at mash temp and 6-1/4 gallons at boiling temps.

If your gravity doesn't drop as expected after boil there's a good chance your volumes are off. Especially if you use more than one vessel i.e. count boiling temps in a kettle and cold temps in a fermenter for example.

 

[DonT]

Are you familiar with water expanding with heat?

6 gallons room temp is about 6-1/8 gallons at mash temp and 6-1/4 gallons at boiling temps.

If your gravity doesn't drop as expected after boil there's a good chance your volumes are off. Especially if you use more than one vessel i.e. count boiling temps in a kettle and cold temps in a fermenter for example.

Well, I'm not coming up short or have too much going into the fermenter.

 

[DonT]

A little more info about my system and process. I have a 3V herms Kal-clone with a Brew Buddy controller. I fly sparge slowly into the BK. Since I hit my predicted numbers in the mash and sparge, I'm guessing my process in those areas is working. I just went through my volumes and everything adds up.
7.5g into BK
1.0g boil off
0.26g shrinkage!
0.75 loss
-------------
5.5g into fermenter (which is what I got)

I was playing with the boil off tool and I changed the evaporation rate percentage to get the "post boil gravity" to match what I got. It gave me a evap rate of 5% for a loss of .38g loss

When I took my readings pre-boil, I mixed it best I could. I also took another reading just before it reached boil, it was churning pretty good so I figured it was well mixed.

What am I overlooking?

 

[bracconiere]

i always find beersmith overestimates my OG by 3 points...but with a hydro temp corrected for 130f, usually a refrac is pretty close....

 

[hotbeer]

5 points is only 2 more points than when I think something might be amiss.

If I was having such issues, then I'd be checking with a hydrometer as well just to easily ensure I'm doing all the corrections with the refractometer correctly.

 

[kevin58]

If 5 points low is close enough for the pre-boil why would expect the post-boil not to be 5 points low as well? You also state that you have more wort than will fit in your fermenter. That tells me you don't have your Beersmith equipment profile adjusted accurately.