Double IPA missed target OG by 20 pts.

[Gunnarburke]

Just brewed what was supposed to be an ~8% double IPA with 1.085 OG and only hit 1.065. see below for the grain bill...my only explanation is that my thermometer is too hot and my mash temp was much lower than intended (148 intended).

Has anyone experienced this? 20 point miss seems insane, as ive always nailed my target OG. I always use this thermometer, but usually my mash is a little higher (152-154), so if the thermometer is off and my typical mash is lower, that might be ok, versus this lower mash temp might be too low.



Any advise? Thanks!

7# 2-row

2# flaked oats

2# malted oats

2# white wheat

.5# carapils

 

[doug293cz]

Need to know what your strike volume, sparge process, pre-boil volume and SG, post-boil volume and SG were to give you and idea of what might have gone wrong.

Making up some typical numbers for a 5 gal (5.5 gal to fermenter), 6.75 gal pre-boil SG, single batch sparge, the best that you could get with 13.5 lbs of grain is an OG of about 1.072. What software did you use to get your 1.085 estimate, and what were your input parameters to that software?

Brew on

 

[Gunnarburke]

Thanks Doug! I used BeerSmith for the estimate.

4 gallon strike volume
4.5 gallon fly sparge at 170

6.5 gallon pre-boil volume, 1 hr boil, 5.25 or so into fermenter. I also added .5# lactose at flameout (which I neglected to mention in the original post).

I used an 83% BH efficiency number in beersmith based on my past experiences and calcs, but this may be slighly high, but not high enough to make up the 20 pt discrepancy I would think

How are you getting to the 1.072 number?

cheers!

 

[Sammy86]

Just brewed what was supposed to be an ~8% double IPA with 1.085 OG and only hit 1.065. see below for the grain bill...my only explanation is that my thermometer is too hot and my mash temp was much lower than intended (148 intended).

Has anyone experienced this? 20 point miss seems insane, as ive always nailed my target OG. I always use this thermometer, but usually my mash is a little higher (152-154), so if the thermometer is off and my typical mash is lower, that might be ok, versus this lower mash temp might be too low.



Any advise? Thanks!

7# 2-row

2# flaked oats

2# malted oats

2# white wheat

.5# carapils

I just put your recipe in BS on my system and got 1.062 thats with 75% BHE. Getting 83% is great...just wondering if maybe you didn't input it properly into BS.

 

[Gunnarburke]

Thanks Sammy! Interesting. After reading your post, I do have a feeling something funky might be going on with my inputs in the software--just cant catch what it is right now. thanks for your reassurance. I will tinker around with it some more when im fresh. Im pretty confident the beer will still be delicious. thanks for your help, Cheers!

 

[grampamark]

I think that the most common causes of significant discrepancies from calculated gravities are either measurement errors, improper inputs to brewing software, or a really poor grain crush. Or, all of the above. The cumulative effect of a small error at each step in the process can add up to a big difference at the end.

Do you weigh and mill your grains or have it done by the LHBS or online supplier? If someone else is weighing the grain do you weigh it again on brew day to confirm the amounts? Do you measure your water volumes or eyeball them? Are your thermometers calibrated? How comfortable are you with 83% efficiency?

Close is good enough for horseshoes and hand grenades but not good enough to hit an exact number in a process with as many moving parts as brewing has.

 

[Gunnarburke]

Yes, totally agree that it is probably a cumulative effect.

just learned (while brewing) that my thermometer may be off up to 5-10 degrees, which is why I was worried the mash temp was too low. I think that is most likely one factor, but you also bring up a good point about the grain crush and weights (grains were milled and weighed by the LHBS, and I didnt check/verify). I am more or less confident in the 83% efficiency, but this could also easily be off a couple points. I think the beersmith calculations are something I need to do some more homework on (especially the lactose flameout addition, which is adding some gravity points and I'm not sure it should).

My main fear was that the thermometer was so off that while I thought I was mashing at 148, it was actually >140 and I was just getting horrible conversion. Thinking about all of the other factors that you and others have brought up here have given me some reassurance that it is probably a sum of inconsistencies that I need to take better account of to be more accurate.

Thanks for the reply!

 

[doug293cz]

...

How are you getting to the 1.072 number?

cheers!

I used my simulation spreadsheet that you can find here. A fly sparge can give significantly better lauter efficiency than the single batch sparge that I used for my estimate. I can't (I don't think anyone can) simulate a fly sparge, but using a triple batch sparge can get pretty close.

Rerunning my simulation using your strike volume, pre-boil volume, and a triple batch sparge puts the max OG at 1.075 - 1.076.

Both simulations assumed 100% conversion efficiency, which is likely to be higher than you achieved if your mash temp was in the low 140's F.

Brew on

 

[DCUSA]

.085 on a 13.5 ib bill with 40% adjuncts seems crazy high. 83% BH efficiency makes you a champ in my mind. I know that with that bill, I would have prayed for even .060 on my igloo system w/ single batch sparge. Did you use rice hulls? From my understanding from brulosophy and genus brewing podcast, hot mash is only going to penalize you a few points. Stirring your mash frequently could be another key to efficiency, depending on your system.

A double IPA is going to have a massive hop bill. The hops alone are soaking up a ton of wort. How much ended up in your fermenter? I know that I would have topped it up with water to hit 5g and been gravely disappointed in the OG.