Undershot OG. What effect will this have on FG?

[morbster]

Hey all, I was brewing up Dude's Lake Walk Pale Ale a little over a week ago and I undershot my OG by quite a bit. Target was 1.068, actual was 1.059.

Brewtarget predicted my FG to be 1.017, but my hydrometer reading today showed a gravity of 1.011.

Is there any useful information that I can deduce from these numbers, or should I simply play the "wait 3 days and take another gravity reading" game?

Thanks.

 

[gr8shandini]

Were you using this recipe straight up, or did you modify it? Your brew appears to be very similar to what he posted.

So, if you followed the recipe, I'd expect a beer that's very much like what Dude intended. If you increased the hops to compensate for a higher OG, it's probably a little hoppy, but you could always just call it an IPA.

 

[morbster]

I intended to follow the recipe exactly, but my LHBS screwed up my grain bill and it resulted in me using a lot more grain than originally intended (hence the larger expected OG).

I think my grain doughed up in the mash, causing my lower-than-expected OG.

I'm just not sure what typical predictions you could make for the FG of batches that begin with a lower OG.


Sent from my spaceship in low orbit.

 

[gr8shandini]

Did the LHBS crush the grain for you? A lot of them run their mills too loose and it's not unusual to get efficiencies in the 60s from them. That could be the problem for your low gravity.

As far as predicting FG goes, there's a lot of variables that go into it. Mash temperature, use of simple sugars or adjuncts, yeast strain, conditions during fermentation, etc. Really, the best you can get is an estimate. At 1.011 you're probably done, but it's always best to wait for a stable FG.

 

[morbster]

Did the LHBS crush the grain for you? A lot of them run their mills too loose and it's not unusual to get efficiencies in the 60s from them. That could be the problem for your low gravity.

As far as predicting FG goes, there's a lot of variables that go into it. Mash temperature, use of simple sugars or adjuncts, yeast strain, conditions during fermentation, etc. Really, the best you can get is an estimate. At 1.011 you're probably done, but it's always best to wait for a stable FG.

I actually had the shop double grind the grains, but I was using 2 lbs more grain than I've ever used in my kettle, and I'm pretty sure I just exceeded its capacity.

Thanks for the input. I'll just check the gravity tomorrow and see how I'm doing.


Sent from my spaceship in low orbit.

 

[william_shakes_beer]

I used to keep a couple pounds of DME on hand to make up the difference if I undershot the OG. Now I just roll with whatever I get. Please verlify you are taking the OG reading after the boil is complete. You're going to go up as water evaporates ( but you already knew that didn't you... never mind)

 

[morbster]

I used to keep a couple pounds of DME on hand to make up the difference if I undershot the OG. Now I just roll with whatever I get. Please verlify you are taking the OG reading after the boil is complete. You're going to go up as water evaporates ( but you already knew that didn't you... never mind)

Yeah, I'm just rolling with my gravities and not worrying about it. Just wanna make sure I learn from my mistakes.

And correct, I take my readings after chilling. I made the mistake of testing the boil gravity (which brewtarget shows). Almost melted my hydrometer wax.


Sent from my spaceship in low orbit.

 

[gr8shandini]

That's where a refractometer comes in really handy. It only takes a few seconds to cool the 2 drops of liquid you need to do a reading. Once you're armed with your pre-boil gravity, the math is relatively simple to figure out what your final volume needs to be to get to your intended OG. These days, I'm always within 2 points on OG which is about as well as I can read my hydrometer anyway.

 

[morbster]

That's where a refractometer comes in really handy. It only takes a few seconds to cool the 2 drops of liquid you need to do a reading. Once you're armed with your pre-boil gravity, the math is relatively simple to figure out what your final volume needs to be to get to your intended OG. These days, I'm always within 2 points on OG which is about as well as I can read my hydrometer anyway.

Yeah, I think a refractometer may be my next gift for myself.


Sent from my spaceship in low orbit.

 

[morbster]

Just a quick question for you. Do you use the refractometer for all pre-fermentation readings and switch to the hydrometer for FG readings?


Sent from my spaceship in low orbit.

 

[kh54s10]

Personally I use my refractometer for all my measurements. But then again I never worry about the actual number of the FG anymore. I just note it. (unless it is would be way off - hasn't happened yet.)

When taking my pre-fermentation readings I note them. I have never made any corrections other than boiling longer once.

 

[gr8shandini]

I usually use my hydrometer for my final, final gravity sample. But that's mainly because I want to have a taste anyway. For some reason a lot of folks are completely against converting a post-fermentation refractometer reading. I really don't know why, though. In my experience, it always gives an answer within a point or two of the hydrometer. We're OK using straight math to calculate something that has a direct impact on flavor like IBU, but somehow calculating a not terribly important number like FG (as long as it's stable, of course) is out of the question.

But I digress. To finish answering your question, I use the refractometer for the pre-boil and OG readings as well as tracking the progress of a lager fermentation to know when to start the D-rest. It's really nice for that since you may have to take samples for 4 or 5 days straight. That adds up to a couple of three beers if you're using a hydrometer.

 

[pablosbrewing]

Just a quick question for you. Do you use the refractometer for all pre-fermentation readings and switch to the hydrometer for FG readings?


Sent from my spaceship in low orbit.

I use my refractometer pre and post and a calculator like this one.

http://www.northernbrewer.com/refractometer-calculator/

I was able to confirm within about .001 to my hydrometer, so I stopped using that altogether.